This is the O.S. Max Number 5 One-Way Clutch Bearing for the Number 5 Recoil Starter Assembly (OSMG8978). This Clutch Bearing allows the recoil starter to grab the crankshaft to start the engine and spin freely in the opposite direction. FEATURES: Pre-installed in Hex Shaped Housing. INCLUDES: One O.S. Max Number 5 One-Way Clutch Bearing for the #5 Recoil Start Assembly. REQUIRES: Placing in plastic housing and installing starting shaft in one-way bearing. SPECS: Width: 0.55" (14mm) Thickness: 0.39" (10mm) Inner Diameter: 0.31" (8mm) JXS 11/16/01 ir/kh