The Benchmade 591BK Boost AXIS Lock Knife Black/Red Black Plain Edge. Benchmade's new Boost is a AXIS-Assist knife featuring a safety lock design. This new 591 model has a black finished CPM-3V premium stainless steel blade with a plain cutting edge. Handles are built with Dark Red Grivory / Black overmolded Versaflex for strength and increased grip. The Ambidextrous Axis Lock and dual thumb studs and a reversible tip-up clip, opposing bevel, blunt pry-tip blade.