Fasst Company's Spoke Torque Wrench Heads are machined to precisely fit your bike's nipple size. Their precise head tolerances minimize the opportunity to damage your nipples when maintaining your wheel. Fasst Company does not produce their Heads to fit multiple nipples like other brands. Short cutting the head applications, making a head to fit multiple size nipples leads to rounded off and damaged nipples, which is not acceptable to them. In fact, other companies that offer spoke torque wrenches design them to fit Fasst Company's heads as they know theirs will fail or they do not offer the actual size head for your nipple.. High quality tool steel. Individual wrench heads that universally fit all Fasst Company spoke wrenches. Absolute precision - Precise fit to your bike's nipple. Vast applications - 12 head sizes available. Lifetime warranty on the wrench and the wrench heads.