Designed for use on the O.S. 28 XZ Truggy engine powering a Kyosho truggy model, this is the Hyper Flywheel Set from O.S. FEATURES: Aluminum construction, black in color Three factory installed, steel shoe pins Steel construction tapered collet INCLUDES: One Hyper Flywheel One Tapered Collet REQUIRES: Installation SPECS: Outside Diameter: 1.38" (35mm) Length: .78" (20mm) from back of flwheel to front of pins OS EnginesPart OSM71813000