This is the spinner nut for the OS 32 SXA, 32FP, and 50FSR engines. FEATURES: Polished aluminum construction Included steel tool for installation Prethreaded for OS crankshafts INCLUDES: One spinner nut One steel rod to crank it down with REQUIRES: Installation onto the crankshaft SPECS: Diameter: 21mm Length: 26mm fits 1/4-28 threaded crankshafts. Comments: This should also fit any OS engine with 1/4-28 crankshafts. 5/14/97 AST kr2/6/04