DMT (Diamond Machining Technology)D3C 3-inch Dia-Sharp Sharpener, Coarse, Credit Card Sized, One Size, (D3F)

This sharpener is great, I've kept it in my wallet since I've got it. It can sharpen up even the dullest blade to hair whittling sharp, provided the bevel hasn't been dented/chipped out--and even then with a little persistence it will actually get the job done. The edge is produces is a nice mix between toothy and polished, making push-cutting easy but also still allowing easy slicing of rope and other fibrous material. Just be sure to use light pressure; the diamonds don't respond well to heavy-handedness. Plus if you press too hard, you will rip them out of the nickle substrate they're bound to, making the hone useless. Don't confuse this for the "break-in" that occurs after several uses; the grit will start to feel smoother, but rest assured it will still do the job--in fact you will get better results once this break-in is complete.The only problem I had with it was that there were some little raised edges, I suppose from where they stamped the card out of a metal sheet. I simply rubbed these off on a flattening stone. Not a very big deal but it will cause a little bit of problems with the sharpening process if not taken care of, but this is so common on most other sharpening media I'm not going to hold it against them.Update:It's now 8 years later, and this little hone has really proved its worth. It's helped for so much more than just sharpening knives. I've chucked-up pins from air rifles into drills and ground down the knurling, and barely burnt out the abrasives on the card. The only downside I can give to this hone is that over time, carrying in your wallet, it WILL go out-of-flat since it's just nickel. Mine now has a bit of a dish in it, but it's not so bad that I can't still hone things on it. Despite all of that, when it comes to things that aren't high-speed ( like chucking up push pins) when you hone normally, this stuff really keeps the diamond abrasives. I've used this from everything from sharpening a knife, honing down knurling on pellet rifle's push pins, to removing gouges out of the locking nuts on double-locking Floyd Rose Bridges. It is an amazing little investment for the price, and I've been able to sharpen very larges items with it over the years too. Machete, kitchen knives, pocket knives, etc. It really only takes a skilled hand and patience to accomplish the edges you need, and as far as having a fine-grained abrasive for other uses, it has stood up to a lot of what I could qualify as abuse. Eight years later, and it's still going strong.

I bought the Fine & Extra-fine versions of this to compliment an ADD Tactical wallet strop loaded with polish compound. All result in a very useful & portable setup that's capable of returning an edge to working conditions while camping or hunting. Do not mistake these for a primary sharpening device as that is not their intended purpose.A couple of pet peeves I have are misleading 'product dimensions' & useless reviews on Amazon. In the text of the 'Description' for this item are the actual dimensions for this item:3-1/4" X 2" X 0.05" (just under 1/16")However, under 'Features & details' it says that the Product Dimensions are 8.5 X 3.5 X 3.5 inches. This is the size of the blister pack (though it's certainly not 3.5 inches 'thick'). This might mislead some to conclude that what they're getting is something bigger.My second pet peeve is the useless negative reviews like 'received wrong item'; 'too small to be much use'; & (my personal favorite) 'didn't work'.How is a packaging error by Amazon any reflection on the product & why do they allow the 'review' to be posted? If you didn't like the size, just return it. If it didn't work, guess what? You're using it wrong! These sharpeners work well but the size & your ability limit how refined an edge you can get.Hope this review helps. Cheers!

I have the red/fine card and the green/extra fine card. If you only get one, get the red/fine. It's the most useful. You can sharpen a blade that is in ok shape in about 30 passes, and one that is in really bad shape in about 80 passes. It takes off just the right amount of metal. If the blade is in really bad shape, you can take off enough to get it back to normal. But it isn't so coarse that one or two bad passes will ruin the edge.The green/extra fine card is really only good for perfecting an already sharp edge. It would be incredibly hard to sharpen a knife using only this card. I would only buy the green card if you already have coarser stones.

Received my fine dmt card today and i was happy with the size and weight immediately. when i seen the picture i thought it would be very thin like a credit card and break easily but this is steel! I did notice right away the little plastic sleeve it came in was ripped but the card itself looked flawless/albeit new and a little rough. I contacted amazon to see if i could replace just the sleeve but was told individual items could not be replaced but they could replace the entire thing and cover the shipping, since its just a little sleeve i didnt think it important enough to do that as the card itself was flawless. so they offered me a partial refund for the inconvenience. great company and customer service.Ok used the card, it works great. a lot quicker than my normal stones. very good size and seems extremely durable

The sticker’s on crooked and the surface needs blown off but I’m sure it will work good