This could well be the ultimate last ditch hide-out blade.  The Ceramic Razor Blade is totally non-metallic, made from Zirconia ceramic, a super-hard material that is extremely wear-resistant.  This covert blade is designed as a hide-out blade for cutting tape, ropes, plastic cuffs, etc.  The blade has a lanyard hole so that it can be sewn into clothing or attached via a lanyard to your belt or gear.  Color: black.  Size: 25mm x 8mm.  Weight: 0.014 oz.