Profile Cr Mo MTB Single Speed Driver Profile Racing's Cassette Drivers are what makes their cassette hubs so great. The 4 pawl design ensures that at least 2 pawls are engaged at all times This means that when you apply power to the pedals, it is instantly transformed into power at the rear wheel, unlike lesser hubs that take a quarter to a half a crank's worth of rotation to engage. Compatible with Profile Mini Hubs, Totem Hubs, High Flange hubs, Madera V2 Cassette Hubs, & Classic MTB Single Speed Hubs. For 3/32" chain It is important to also replace your chain whenever you install a new driver. A worn, stretched chain will cause your driver to wear out much faster. Pawls & springs not included (sold separately) Buy Profile Wheels & Tyres from Chain Reaction Cycles, the World's Largest Online Bike Store.