This Kershaw oversized pivot is hollow in the center, letting you see through it. But a regular hex or torx tool wont work to adjust it. To meet the need that just about every knife user has to tinker, Kershaw STPTOOL answers the call. Its 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.