This is a review of a Bud K Neck Knife that I've owned for a few years. I mostly wear it when walking my dog along the trails in the woods beside my neighborhood, as well as when I go jogging. But it could be used for numerous other purposes, too. In addition to the knife, the sheath has a built-in whistle, which could be very useful in certian circumstances.
This knife is surprisingly inexpensive (less than $10) for its quality. Here are the details: total length of the tanto-style knife itself is 6.75 inches. The cutting edge is 3 inches. In its sheath, it checks in at 7.5 inches. It is designed to be quite light weight, with the knife, sheath, and cord combined weighing less than 3 ounces. The full-tang knife is a black anodized 440 stainless steel. It came out-of-the-box relatively sharp. Overall, both the knife and the sheath & whistle seem well-made.
The knife snaps in place upside-down in the ABS sheath, which hangs by a cord from your neck. You can adjust the cord so that the knife hangs at the desired level on your chest. You could also easily replace the cord with different cordage or even a ball-chain if you wished. The sheath has a built-in whistle, which is quite loud.
The snap-in system works quite well. I've had this knife for almost four years, and have never had it fall out of its sheath, even when I'm being quite active. It still seems to hold as firmly and securely as when I first got it.
This shouldn't be your primary fixed-blade knife, of course, but it works great for my purposes. Use it for when you don't won't to wear a belt knife (such as I do when walking my dog or jogging), or to have as a back-up. It is light enough to throw into a backpack, book bag, pocket book, or brief case without adding a lot of weight. It would also fit nicely into the glove compartment or door pocket of a vehicle. For these purposes, I give this neck knife a 4.5 out of 5 stars.
It is currently available on Amazon for less than $10, which I consider a good buy for this neck knife.