These cool and unique custom made self defense keychain tools are built one at a time by hand in Canada. They are strong, lightweight and virtually indestructible completely construction of 40,000 PSI G10 fiber and sharpened to an edge that will cut to the bone on impact. Drop one in your watch pocket to avoid detection or have it ride silently on your keyring until needed and you have some serious personal prouction in the event your personal safety becomes at risk.... 2.5AOL, 1/2 ounce and the ID on the knuckle hole is .88" (22.5MM)