FSA HEADSET GUIDE TOOLGOING FULL SPEED AHEADHeadsets can be tough to figure out. Different bikes will use different headset standards, so you need to figure out which standard your bike uses. The FSA Headset Guide Tool lets you quickly and easily determine the bearing that will fit in integrated headtubes and find replacement bearings for internal headsets. It features gauges for all current headset cartridges bearing standards, 1" to 1-1/8". Features Measures inside the headtube or bearing cup diameter and out bearing angle Gauges for all current headset cartridge bearing standards from 1" to 1-1/8"Quickly and easily determine the bearing that will fit in integrated headtubes | Fsa | Headset Guide Tool 1", 1 1/8"