Mongrel D2 Tool Steel Original Filipino Balisong butterfly Knife BF-81

The BF-81 Mongrel is a 29cm full-size Filipino balisong with a 14cm D2 tool steel blade, brass handles with kamagong wood inserts, 220 grams. It is the plainest of our full-size knives and the least expensive of them, and it is for someone who wants the traditional dimension without paying for handle material they do not care about. Trainer available at the same price above Add to Cart.

A knife called Mongrel is not asking to be admired

We could have written something about how the mongrel is the hardiest dog, tempered by the street, unbowed by pedigree. We are not going to, because you would see straight through it and because the word means what it means.

A mongrel is the unglamorous one. It is also, usually, the one that is still going when the show dogs have developed hip problems. That is roughly the argument for this knife.

It is the same 29cm frame, the same 14cm D2 blade and the same 220 grams as the two knives above it in this run. What it does not have is bone or horn. It has kamagong, which is the sensible material, and it is eleven dollars cheaper as a result.

The full-size knives in this run, priced honestly

Since the whole point of this knife is where it sits, here is the comparison in full.

All four are 29cm open with a 14cm D2 blade. The steel is identical across the row. What you are choosing between is handle material and, on the Monkey, frame metal.

If the blade is what you came for, this row should make the decision fairly easy.

Kamagong, the unshowy choice that outlasts the pretty ones

Kamagong is Philippine ironwood. Dense enough to sink in water, tight-grained, and hard enough that it dulls tooling on the way to becoming a handle insert.

What it gives you on a balisong is dimensional stability. Horn and bone are lovely and they are also alive to their surroundings: they move with heat and dryness, and a badly stored horn handle can check over a few years. Kamagong sits there. Humidity swings do not shift it enough to change the tolerances around the pivot, which is the thing that actually determines whether the knife still feels right in a decade.

It also does not need seasonal oiling, does not object to a hot car, and does not vary dramatically between one knife and the next. That last point is worth something if you have been burned by a natural-material knife arriving in a colour you did not expect.

What 220 grams on a 29cm frame is actually like

Twenty-nine centimetres is the traditional Batangas measurement, the veinte y nueve, and it is noticeably more knife than the 24cm frames most shops sell as full-size.

The rotation is longer and slower. The momentum, once you have it, is considerable and does most of the work for you. The flip side, and it is a real one, is that a movement that starts badly has more mass behind it and less time to be corrected.

For an experienced flipper this reads as authority. For a beginner it usually reads as an expensive lesson. If you are new, order the trainer and spend two months learning on it, then buy the sharp version if you still want it.

D2 on a butterfly knife, and who it suits

D2 is a high-carbon, high-chromium tool steel running near 60 HRC. It holds an edge several times longer than the high carbon blades elsewhere in this series and it resists corrosion much better.

The price is sharpening. D2 does not want a ceramic stone, it wants diamond, and even then it takes its time. That is not a defect, it is the same hardness that gave you the edge retention refusing to give it back easily.

So: high carbon if you like sharpening and want the finest possible edge. D2 if you want to sharpen the thing twice a year and otherwise leave it alone. We make both because both are correct answers to different questions.

Ordering this D2 butterfly knife

The trainer version has no edge, weighs the same, costs the same, and is selected above Add to Cart. Same price because removing one grinding operation from a long build does not make the build meaningfully cheaper.

A fitted leather sheath is in the box. It is a plain one, cut to the frame and not tooled or stamped, which suits a knife called Mongrel rather better than anything decorative would.

US shipping is free. Everywhere else is a flat $49 for the entire order, so it is worth consolidating if you are ordering from outside the States. Check your local knife law before you order.

the D2 is taken to 58-60 HRC, the same hardness we use across the whole shelf.