The Kershaw STPTOOL was designed for use on the Kershaw Flythrough (1988) and the Zero Tolerance 0609. The STPTOOL is made of stainless steel and it has a titanium carbo-nitride coating. The overall length of this item is 2.75 in. and it weighs approximately 2.2 oz. The Kershaw Flythrough (model 1988) and the Zero Tolerance 0609 both feature RJ Martin’s unique “See-Through Pivot (STP).” This oversized pivot is hollow in the center, letting you “see through” it. But a regular hex or torx tool won’t work to adjust it. To meet the need that just about every knife user has to tinker, Kershaw introduced STPTOOL. It’s specifically designed to let you adjust the STP on the Kershaw Flythrough and the ZT 0609 so you can have things as loose or as tight as you prefer. Tinker away.