SOG Pentagon FX Fixed Blade Knife 4.77" S35VN Black Double Edge Dagger, Flat Dark Earth G10 Handles, Kydex Sheath - 17-61-02-57
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$149.95

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MSRP* : $289.99 | You Save* : $140.04 (48%)
rated 3.2 stars out of 5 Read 4 reviewsWrite a Review
Part #: SOG17610257 | SOG Knives and Multi Tools
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Description

SOG17610257: 17-61-02-57 Pentagon FX Fixed Blade - Flat Dark Earth

SOG Knives

Representing an evolutionary step in hard-use fixed blades, Pentagon FX is a full-sized knife made for the modern-day warfighter. It features a double-edge CYRO CPM-S35VN full-tang steel blade, removable G10 handles, and a GRN sheath compatible with SOG's next-generation Universal Mounting System. It's fully customizable to meet the demands of various missions and purposefully designed to exceed expectations.

Pentagon FX’s sheath system isn’t the only thing that’s adaptable. The handles can also be removed for a slimmer profile. The Pentagon FX comes with multiple accessories from SOG’s Universal Mounting System. It allows for a flexible mission-specific set-up, including adjustable sheath retention, secondary retention, mounting angle, mounting method, and combinations of each.

Specifications

  • Blade Length: 4.77"
  • Handle Length: 5.16"
  • Overall Length: 9.93"
  • Blade Material: CRYO CPM-S35VN Stainless Steel
  • Blade Thickness: 0.180"
  • Blade Hardness: 58-61HRC
  • Blade Style: Double Edge Dagger
  • Blade Finish: Black Titanium Nitride
  • Handle Material: Flat Dark Earth G10
  • Sheath Material: GRN with Universal Mounting System
  • Weight: 6.5 oz.
  • Made in Taiwan

UPC Code: 729857011518

Related Categories

SOG Knives and Multi Tools, SOG Pentagon FX Daggers Series, S35VN Blade Steel, G10 Handle Material, Fixed Blade Knives, Fixed Blade Knives Daggers

Badges

Product Handle Badge: G10 Handles
Product Sheath Badge: Kydex Sheath
Product Steel Type Badge: S35VN Stainless Steel

Customer Reviews

SOG Pentagon FX Fixed Blade Knife 4.77" S35VN Black Double Edge Dagger, Flat Dark Earth G10 Handles, Kydex Sheathrated 3.250 stars out of 5 (4 reviews)
3.2 out of 5 stars
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SOG Pentagon FX Fixed Blade Knife 4.77" S35VN Black Double Edge Dagger, Flat Dark Earth G10 Handles, Kydex Sheath
rated 3 stars out of 5
Brich
 Tampa, FL
Apr 11, 2025
Pros: Blade Material
Cons: Blade Sharpness, Sheath/Scabbard
Ditto
I spent weeks with a spyderco duo hone trying to sharpen my FX. I never did get it to the sharpness that I like. The tip is OK, but the edges are just difficult. The sheath is also overbuilt and not as flexible as SOG might think. For this price point, I would expect small ergo issues to have been identified in the design phase and fixed. The final product should polished and vetted. I like the SOG pillar much more for all of these aspects.
SOG Pentagon FX Fixed Blade Knife 4.77" S35VN Black Double Edge Dagger, Flat Dark Earth G10 Handles, Kydex Sheath
rated 3 stars out of 5
Rascal
 Utah
Mar 08, 2025
Pros: Blade Material, Finish, Handle Material, Materials, Sheath/Scabbard, Weight
Cons: Blade Sharpness, Overall Quality
like he said... it's a project.
Very expensive dagger... probably not ideal length, (would like to see at least 5") grip is pretty good but blade is dull as can be. This is a harder steel and you will have to put your own edge on BOTH SIDES. Sheath is a little cumbersome with that rubber wrap around portion. Taking the blade OUT is not a problem with the flip of your thumb IMHO so there's that... it's just a bit of a pain putting it back in and securing it with said rubber loop. I've got a SOF background to go with knife fighting and work in the medical field and know my human anatomy. You WANT razor sharp edges on your dagger. Once inside a body, you want to be able to create maximum damage and you do that by slicing everything you can on the inside of the body. Moving the tip back and forth and sliding along the bottom of a rib is ideal. (bottom of the rib is where the nerves and blood vessels are located). if you're willing and able to put razor sharp edges on this thing... i think you've got a pretty good dagger going for you. I believe the point on this thing is capable of standing up to your hardest thrusts against a ballistic helmet or body armor in a fight, whereas other cheaper daggers with less favorable/capable steel and thinner blade geometry will likely snap/break off. THAT and the slightly more favorable grip on this dagger are the only things it really has going for it when you're deciding to pay more for this dagger over something else. For example, the Cold Steel Wasp is longer and probably sharper but i can't vouch for that grip or tip... you just have to decide what is right for you based on what you require of your dagger.
SOG Pentagon FX Fixed Blade Knife 4.77" S35VN Black Double Edge Dagger, Flat Dark Earth G10 Handles, Kydex Sheath
rated 3 stars out of 5
Will
 Mountain South
Jul 21, 2022
Pros: None
Cons: None
Create your own edge project, and Sheath peculiarities
I had initially purchased the covert model, and found I liked the ruggedness of the design, so, I bought the larger version as well. My intention is to have a strong multifunctional blade with a spare edge so that if one side becomes dull, I can simply switch to the other edge. with the exposed metal of the handle I would still be able to baton, and the penetration capability of a dagger blade would be an added bonus in an extreme emergency. I've had a lot of experience with flat ground blades and prefer them for utilitarian uses. What is unusual about these knives is that they are not very sharp out of the box. I've purchased axes that had a more honed cutting edge. I very much value a razor sharp blade, especially on a military style model. The edge on this full size FX is in better form that what my covert was, and I've not had to completely re-edge the knife. After several hours with diamond, carbide, and ceramic sharpening tools, and as much on a strop with 4 grades of compound, so far... I have a knife that is not quite razor sharp, and hope that I will be able to achieve a nice mirror finish razor edge on this blade without the crazy amount of work I put into my covert version. The point itself isn't perfect, but it does have a strong diamond shape, and most importantly has the thickness and spine to be used as a dagger is intended. Given the quality of the workmanship on the knife I have a hard time justifying the cost. The sheath is overly specialized in its attempt to answer complaints over other poorly designed sheaths. The adjustable tension system I could do without. as well as the strap, and the UMS clip. I think they should be offered separately as a specialized sheath for those who want those capabilities. having eye rivets in the top of the sheath would be much more useful for most people. The clip on the covert sheath would not be bad at all on the full sized scabbard either in my opinion. Overall it is a good knife, but it is a project, and that is not something a person at this price point at this time in history is probably going to look favorably upon.
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