We tend to focus on a certain core group of attributes when we’re reviewing knives. What steel is it? How strong is the lock? How much does it weigh? What’s the blade shape like? A lot of knives are seemingly made to a formula involving several of these attributes, designed to hit a target that produces a certain number of sales. This is why a lot of new knives these days seem very similar. But SOG likes to do some weird stuff from time to time. That’s how we wind up with the SOG Ultra XR, the design briefing for which probably went something like this: “how thin can we make this knife? Yeah, the whole thing. Can we make this knife thinner overall than the blade stock on a Medford?”
Seriously, it’s not far-fetched. The SOG Ultra XR’s handle is 0.2” wide. The Medford Midi Marauder’s blade is 0.19” wide. The SOG Ultra XR is a study in absolute minimalism… except it’s absolutely not, because it’s loaded with interesting materials and technology to reach its crazy thin/light specs. The Ultra XR is actually the second generation of the SOG Ultra, the first being the Ultra C-Ti.
With the change to the second generation, the Ultra replaced the old Arc-lock (which I was never much of a fan of) with the XR lock, it got a new clip, revised handle shape to ditch the finger grooves, and upgraded steel. The Ultra XR is a very strange knife, because it functions perfectly well as a pocket knife – but it’s thin and light enough to be a money clip. Let’s take a look and try to unravel this unusual pocket knife.
Key Specs: SOG Ultra XR
The blade on the Ultra XR is, understandably, very thin. It measures 0.08” across, making it one of the thinnest blades on a dedicated pocket knife I’ve ever seen, along with the Spyderco Chaparral. It’s a clip point blade shape, with a medium height flat grind for the primary grind, and a false swedge along the concave spine towards the tip. The blade measures 2.75” long with a 2.625” cutting edge and is 1.125” tall at the widest point. The ultra-thin blade stock minimizes the impact that the relatively chunky geometry of the blade (this flat grind is more like a Scandi grind than a sabre grind, it’s rather low!) has on cutting performance.
The sharpening choil – if it can be called that – is quite odd, the plunge line from the flats curving down to intersect the steeply rising choil. There’s absolutely no beard or unsharpened steel on the edge of this blade, which you love to see, but also that basically 90 degree choil that goes up about a third of the height of the blade is guaranteed to trap whatever material you’re cutting – it’s a mixed bag.
The Ultra XR is currently available in two versions – a flat grey which looks pretty normal, or this gold Titanium Nitride coated version, which is an acquired taste – to put it politely. Some people love the matte gold hue and some people do not. I find it interesting, which is a phrase loaded with its own connotations. Blade steel on the Ultra XR was upgraded to CPM S35VN from the original version’s VG-10, which is a big step up in terms of edge retention and hardness.
S35VN contains around 50% more carbon than VG-10 (for edge retention) and about twice as much molybdenum (for hardness and fine grain size) as well as a large amount of vanadium (VG-10 containing basically trace amounts) which aids in hardness and small grain size as well. Meaning, S35VN will hold an edge longer as well as take a cleaner, smoother finish to the edge when you sharpen it. It’s a much more modern, high-performance steel – while still retaining the positive corrosion resistance abilities that VG-10 boasts.
Deployment and Lockup
The main upgrade from Ultra C-Ti to Ultra XR was the adoption of the XR lock. I’ve only ever tried one knife with the Arc-lock, and I really didn’t like it. The XR lock has effectively replaced the Arc Lock, and is better in basically every way – especially if you’re a lefty, since the XR lock is ambidextrous and the Arc-Lock was for righties only. Unlike the other XR lock knives, the Ultra XR doesn’t use ball bearings in the pivot – because they would make the knife considerably wider – so it’s not as smooth opening and closing as other manual XR knives like the Terminus and SOG-TAC XR.
Opening is via an oblong thumb hole shaped like an oval, or by pulling the lock release backwards and wrist-flicking the knife. There’s not enough real estate around the thumb hole to flick it open from the back – I’ve tried – but you can flick it open from the front with some practice. The super narrow build of the knife makes it somewhat awkward to attempt this with, like you’re always on the verge of dropping it. A slow thumb roll open is easiest and the least anti-social, to be certain.
SOG claims this lock can withstand 1500 pounds of pressure, which definitely raises some questions. Like, where? In what direction? Why? Who is hanging 1500lbs of weight from the blade of a 1.2 ounce knife? I didn’t test this claim out for fear of bodily injury. I will note lockup on this knife is a little sloppy, no play vertically but a significant amount side-to-side, even with the pivot screws tightened all the way down. I guess this knife isn’t really intended for batoning cords of wood, so it’s probably not a priority.
To make the knife this thin, the design of the XR lock has been changed a bit – instead of separate omega springs (or double omega springs) on each side like the full sized knives, the Ultra XR uses a single coiled spring mounted on its own standoff pin to drive the lock bar forward – the pin behind the stop pin, in case you wondered why this knife has two body screws above the lock release. This means that the pin wobbles from side to side like the bad old days of the Arc-Lock since it doesn’t have two separate springs providing equal pressure to both sides. Still, the external stop pin provides solid vertical location of the blade when open, and this pared-down setup works just fine for opening mail and trimming strings, which are the hardest activities these knives are inevitably going to perform.
Features, Fit & Finish
The Ultra XR certainly is an interesting knife. Keeping a knife this thin and light is a feat of engineering itself, so the handles are worth a mention. They’re paper-thin and there are no liners, but the scales themselves are solid pieces of 3D machined carbon fiber, with a shimmering weave pattern under a pretty lustrous finish. The lack of any liners is what keeps the knife so paper thin and light. If the pocket clip seems unnaturally huge for the Ultra XR it’s because it serves a double purpose as a money clip as well as a pocket clip.
The pocket clip is mounted by two screws on the butt of the handle, looping all the way over the top (so it’s total deep carry, ie none of the handle is visible in the pocket) and it’s ambidextrous tip up carry- the screws only pass through the scale and thread into the clip, so there are countersunk screw holes on the opposite side to flip it if need be. All the screws are standard Torx sizes if you want to disassemble or maintain the knife, with the two clip screws, two body screws, and the screws locating the stop pin and the anchor pin for the lock spring towards the front, as well as torx fittings in the pivot and the lock bar itself – it’s kind of a lot of fasteners for such a small, light knife.
The knife is fully ambidextrous though, with a lock, clip and opener that works the same left or right handed. And of course, both the blade and the pocket clip are titanium nitride coated the same flashy matte gold color that would have looked at home on a Lamborghini at SEMA circa 2007. Branding is much less over the top now that SOG has started going by “Studies and Observations Group” – which is found on the left side of the blade, above the model name and steel type. There’s no writing on the reverse side, and just the letters “SOG” on the clip.
The main issue I have with the Ultra XR is fit and finish. This is a shame because most of the recent SOG’s I’ve handled have been very well made – but there are some glaring problems with this knife. The biggest crime is that the right side of the blade rubs against the inside of the scale when you open the knife with your thumb, due to the side-to-side play in the pivot and the super narrow handles. Since this is the coated version, there’s a black rub mark on the side of the blade where the primary bevel intersects the flats, like the blade is rubbing off the carbon fiber handle. I haven’t been able to correct this with any amount of fiddling with the pivot or body screws. This also results in a gritty feeling deployment and some teeth clenching noises too.
The myriad of body screws are a mess, none of them sit at the same height when tightened down, some standing pretty proud of the scales and others sunk rather deep in. The titanium nitride coating on the blade looks great but I also wish SOG had spent more time getting the knife sharp – this is also the only SOG I’ve had that didn’t come very sharp from the factory, and S35VN requires a good bit of work to rectify. These fit and finish issues are a bummer and ended up keeping me from carrying the knife as much as I thought I would – SOG has set the bar pretty high with their more recent products (especially the Terminus XR) and this doesn’t hit it.
Well, the Ultra XR does one thing very well – carries. This knife is impossibly light and thin, and the pocket clip is very effective at retention. It’s fully submerged in your pocket thanks to the loop-over-the-top style clip, and the wide stance of the clip (which is also designed to work as a money clip) makes it very stable in the pocket. It’s small enough that you can easily fit other stuff in the same pocket – cell phone, keys, etc – that you couldn’t comfortably do with a larger folder. And it’s so light you’ll forget it’s there – make sure you don’t put it through the washing machine with your jeans.
Of course, the small size comes with some limitations. It’s a little awkward to open because it’s so thin, requiring precise placement of your thumb on the narrow opening hole without putting too much pressure on the blade. It’s not particularly ergonomic either, although the redesigned handle shape is much more neutral than the old one, but the super-narrow handle feels odd in your hand when you’re cutting things. The jimping on the spine of the blade helps to maximize traction, which is good because the handle is effectively a three-finger grip if you have large paws. The oversized clip relative to the handle quickly becomes a hot spot when you’re using the knife.
The blade is pretty useful, being long enough to do most day-to-day tasks and thin enough to slice well. The titanium nitride coating is very smooth and hasn’t rubbed off with casual use. I do think the knife would perform better if it were full flat ground, but that’s probably more theoretical than actual as it’s still such a narrow piece of steel.
All these knives available at BladeHQ.The most interesting thing about the Ultra XR is how few similar products there are. I can’t think of anything that’s exactly like this knife. But let’s look at ultralight folding knives in and around a $125 retail price. So, under two ounces, blade length between 2-3”.
The most obvious competitor is the Benchmade Mini Bugout, ringing in at $119 for the orange version. It’s similarly Lilliputian: 2.875” blade, 3.71” handle, weighing in at a shockingly light 1.5 ounces. It uses the Axis lock, the progenitor of the XR lock, but here Benchmade has the advantage: the Mini Bugout uses dual omega springs to provide tension to the lock bar for even lockup. Blade steel is CPM S30V, which is theoretically a step down from S35VN, but in practice both steels work great – and both blades are similarly razor thin, the Benchmade clocking in at 0.09” blade stock to the SOG’s 0.08”. The Mini Bugout is about 0.4” longer overall than the Ultra XR but the handle is twice the width, 0.42” to the Ultra’s 0.2” and it’s only 0.3 ounces heavier, so the enhanced ergonomics are probably worth the slight extra weight.
As mentioned earlier in the article, the Spyderco Chaparral Lightweight is a contender. It’s heavier – at 2.0 ounces – and the handle is wider – at 0.32” – but both have 2.8” blades cut from 0.08” wide blade stock. The Chaparral uses CTS-XHP steel, which is an excellent high end tool steel, and benefits from a full flat grind on the blade for maximum slicing ability. The textured FRN handle scales offer better traction than the slick carbon fiber of the Ultra XR, and the Chaparral has my favorite pocket clip of all time: Spyderco’s deep carry wire clip. It seems like a bargain at $95, but there’s no fancy carbon fiber and it uses a more pedestrian back lock so the fidget factor is lower.
For something a little funkier, the Civivi Knives McKenna, designed by Elijah Isham, offers a superlight compact folding knife with sleek modern lines. Weighing in at 1.75 ounces, the McKenna uses ball bearings and a front flipper for deployment, and has a 2.875” flat ground Sheepsfoot blade in D2 steel. Handles measure 0.40” wide, and a stamped steel deep carry clip keeps it in place. A very cool option for $68.
Finally, the knife the Ultra XR reminded me of from the start: the Victorinox Swiss Army money clip. My dad carried one of these for years, and then another one when airport security confiscated the first one. The super wide clip on the back side does a great job retaining bills, and the money clip has a plain blade, a set of sprung scissors, and a nail file with a nail cleaner. Handsome Alox scales and a $40 price point make this an attractive gift when dad loses another one at a courthouse or something.
The SOG Ultra XR is an exercise in “look what we can do!” and I appreciate that about it. It’s ridiculously light and thin for something with a real lock, and it’s striking to look at. I don’t carry cash, ever, so the money clip functionality is lost on me, but the wide pocket clip works great at holding the knife in your pocket. If you were a gram-counting ultralight backpacker type this knife is probably worth considering (along with the Benchmade Bugout/Mini Bugout) but for an everyday carry knife it’s just too thin to use comfortably.
My main issue with this knife was with quality though, not design. There are more rough edges and issues than I’ve come to expect from newer SOG’s, especially at this price point – I get the price point given the exotic materials, but also the blade shouldn’t ever rub against the scales with the pivot tightened down. A little more attention paid to quality would not go amiss on this otherwise fascinating product.
- Impressively light and thin for a knife with a real blade and a lock, premium materials, eye-catching looks
- Super-thin doesn’t translate to “pleasant to use”, fit and finish issues unacceptable at this price point, pricey.