Designed for all out racing conditions these tensioners are machined from 304 Stainless Steel Billet Aluminum Pulley Is Machined from 7075 and Hard Anodized with PTFE Added for Reduced FrictionDouble Roller Bearings for the High Reving Race EnginesSpring Pin is Our Custom Billet Should Pin Machined from 304 Stainless, Not A Cheap Spring Pin