VMP Performance 2.9? 6-rib bolt-on supercharger pulley for VMP TVS supercharger kits. GripTec L3 finish on ribs and black anodizingAmerican made with high-quality anodized aluminum constructionUtilizes 6-bolt hub patternFits VMP, Roush, and Odin superchargers. It is recommended to use race fuel with this pulley. Injector and fuel pump upgrades are required.As a general rule, 1 PSI boost is equivalent to 3 mm or .1? in pulley size Includes (1) bolt-on pulley VMP is proud of its growing line of pulleys. GripTec Micro technology is a micro ablation machining process applied to the ribs of the pulley giving them maximum gripping force. The multi-directional machined ridges minimize belt slippage. Manufactured in the USA, using high-quality anodized aluminum, VMP?s pulley is made with strength and durability in mind. Precision machined, this pulley has an excellent fit. Hub NOT included.