www.sog-knives.net The SOG Twitch XL Tanto knife has an AUS 8 stainless steel blade and a black hard anodized aluminum handle. This SOG TWI-221 model opens with the SOG Assisted Technology. This consists of a coil spring to help open the blade once the user activates the thumbstuds or the kick on the spine of the knife. The SOG name has been inscribed on the reversible pocket clip that is mounted in the end of the handle.