Park Tool Bicycle Headset Wrench 36mm/40mm HCW 9

36mm and 40mm head wrench. Our popular and versatile Head Wrenches feature our proven Y head design and all headset wrench openings are lazer cut to ensure a tight, accurate fit. Precise sizing is achieved by high voltage computer controlled lazer technology after heat treat. Waiting until the wrench is heat treated eliminates shrinkage and expansion of the steel after the wrench is sized. It takes longer, and costs more, but its worth the extra effort.