Black Steel Key CacheWhy It Made The List A sleek, precision made piece of everyday carry, this key cache is machined to the same high standard Wingback bring to all their hardware. The Black Steel version is finished with an ultra hard, scratch resistant 4m tungsten carbide layer that is nine times harder than stainless steel and normally found on high performance cutting tools. The threaded compartment opens cleanly and seals tight, keeping whatever you store inside dry