SOG Specialty Knives and Tools (SOG) was founded in 1986 by designer and toolmaker Spencer Frazer. Named after the elite Vietnam-era multiservice special operations unit. known as the Military Assistance Command, Vietnam — Studies and Observation Group (MACV-SOG), the company’s first knife was a replica of the original MACV-SOG Counter Insurgency Support Office (CISO) issue Bowie knife. SOG was acquired by GSM Outdoors in December 2021.

The SOG Pentagon XR™ is easy-to-carry full-size tactical folder that is optimized for self-defense and combat. The Pentagon XR is designed to offer compact manual folding alternative to SOG’s Pentagon FX Covert fixed-blade dagger and Pentagon OTF automatic knife. SOG also offers a lightweight version of the Pentagon XR, the Pentagon XR LTE that is 35% lighter than the standard Pentagon XR. The XR in the name refers to the locking mechanism.

Built for professionals, the Pentagon XR is designed with a focus on defense and combat use.

The SOG Pentagon XR was designed specifically for professional users: first responders, law enforcement and military. The knife is the direct result of insight and feedback provided by SOG’s cadre of subject matter experts, according to Jonathan Wegner, Vice President of Brand for SOG. It was designed in the US and is built in Taiwan.

The Pentagon XR is a robustly built knife that features a 3.60″ cryogenically heat-treated Carpenter CTS XHP stainless steel (59-60 HRC), 1.00″ wide spear point blade with a matte-black titanium nitride finish. Titanium nitride is typically very durable. The blade is 0.12″ thick. The knife has an overall length of 8.38″ open and 4.77″ inches closed. It weighs 4.9 ounces.

Carpenter CTS XHP stainless steel is a high-performance alloy that combines the corrosion resistance of stainless steel with the wear resistance of tool steel. It has a high carbon content (1.6%) and a high chromium content (16%), which give it excellent edge retention and hardness. It also contains small amounts of molybdenum, vanadium, and cobalt, which enhance its toughness and resistance to chipping. It can be thought of as either a high hardness 440C or a high corrosion resistance D2 tool steel. It is a premium stainless that’s also considered to be one of the “super steels.” It is used in high-end cutlery and applications requiring a high degree of corrosion resistance and wear resistance.

Pentagon XR has a 3.6” spear point blade made of CRYO CTS XHP stainless steel for corrosion resistance and edge retention. G10 handle on Pentagon XR is exceptionally ergonomic and provides excellent grip.

SOG went with CTX XHP for the Pentagon XR since it, according to SOG, “provides” the ideal combination of edge retention and durability for heavy use with minimal maintenance.” CTS XHP offers great edge retention and exceptional corrosion resistance. It is reasonably tough considering its high hardness. It is also harder to sharpen due to its hardness.

The plain edge spear point blade provides a good balance between piercing and slicing ability. It concentrates 100% of the thrust force along the exact centerline of the knife. It combines the sharp point of a dagger with the strength of a drop point blade, while retaining some of the belly of the latter for cutting and slicing.

The blade features a deep fuller on both sides and has a small, sharpened back edge for enhanced penetration and delicate work. Technically, the sharpened back edge, albeit small, potentially puts the Pentagon XR in the double-edge knife category from a legal perspective. The Pentagon XR came razor sharp out of the box.

The Pentagon XR is designed for single-handed ambidextrous operation. All functions are accessible with either hand. It offers you three modes of ambidextrous opening to suit your preference: thumb studs, flipper and inertia opening. It features a ball-bearing pivot system to reduce friction and allow for smooth and rapid deployment.

Ambidextrous XR lock on Pentagon XR is capable of withstanding 1,500 lbs. of force. The Pentagon XR offers three modes of opening: flipper, ambidextrous thumb studs and inertia.

The patented XR locking mechanism is strong and completely ambidextrous. It allows you to close the knife without ever placing your fingers in the path of the blade. It also allows for easy inertia opening by simply holding back the lock and flicking out the blade. Lock up is very solid, with absolutely zero up and down blade play and only a miniscule bit of side-to-side wiggle in the sample knife,

The XR lock works using a small, hardened steel spring-loaded transverse round bar (crossbar) with sliding buttons that moves in a machined groove in the liners and engages a notch in the tang of the blade when the knife is opened. The bar is held in place by the hardened stainless-steel liners. The stop pin positions the blade for additional strength and reliability. The XR lock mechanism also serves as a detent to hold the blade in the closed position. According to SOG, the XR lock is able to withstand a whopping 1,500 pounds of force. The XR lock is self-adjusting for wear.

The handle is of partially open back design and has “Ultra Grip” G10 scales with radiused edges. The Ultra Grip texturing provides a very “grippy” slip-resistant grip without being so aggressive as to be hard on pockets. The G10 scales look great too. It is available with either black (Blackout), OD Green or Wolf Gray G10 scales. I went with the Blackout model. Stainless steel liners are nestled in recesses machined into the knife’s scales to reduce handle thickness and provide support for the XR lock. The liners are skeletonized for weight reduction.  

Pentagon XR has a reversible pocket clip for right or left hand tip up carry.

The Pentagon XR is equipped with a reversable low-profile heat-treated stainless-steel flat-wire clip for right- or left-hand tip-up carry. The design of the clip is aesthetically pleasing and allows for easy in and out of pockets, even those with a thick pocket edge, yet is very secure. The butt of the handle is roughly 0.5-inch above the top of the clip, making the knife easy to grab in high stress situations.

The Pentagon XR feels great in the hand. It is well balanced. The handle has a neutral shape except for a large finger choil. The choil serves to index the knife and provide additional security in the hand. There is jimping ion the top and bottom of the handle in all the right places. The flipper also serves as a handguard to protect your hand. The flat clip doesn’t create any hotspots when the knife is gripped.

The Pentagon XR is a rugged, well-built, aesthetically pleasing knife, with excellent ergonomics. It holds an edge very well. Fit and finish on the Pentagon XR are excellent. The Pentagon XR has a MSRP of $174.95. It has a limited lifetime warranty. If you are in the market for a great tactical folder, definitely check out the Pentagon XR.


SOG Specialty Knives & Tools (SOG)

GSM Outdoors

SOG Pentagon XR

Brand: SOG
Product Type: Manual Folder Knife
Model: Pentagon XR
Overall Length: 8.38″
Blade Length: 3.60″
Blade Width:1.00″
Blade Thickness: 0.12″
Blade Material: CTS XHP Stainless Steel
Blade Style: Spear Point
Blade Grind: Flat
Finish: Black Titanium Nitride
Edge Type: Plain
Opening Mechanism: Inertia, Ambidextrous Thumb Stud, Flipper
Locking Mechanism: XR
Handle Length:4.75″
Handle Width:1.25″
Handle Thickness:0.55″
Handle Material: G10
Handle Color: Black, OD Green or Wolf Gray
Weight: 4.9oz.
Country of Origin: Taiwan
Best Use: Tactical, EDC
Warranty: Limited Lifetime
MSRP: $179.95 USD

Material Disclosure

I received this product as a courtesy from the manufacturer so I could test it and give my honest feedback. I am not bound by any written, verbal or implied contract to give this product a good review. All opinions are my own and are based off my personal experience with the product.

*The views and opinions expressed on this website are solely those of the original authors and contributors. These views and opinions do not necessarily represent those of Spotter Up Magazine, the administrative staff, and/or any/all contributors to this site.

By Eugene Nielsen

Eugene Nielsen provides intelligence and security consulting services. He has a bachelor's degree in political science from the University of California. His byline has appeared in numerous national and international journals and magazines.

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