This is the Great Planes ElectriFly 6mm Prop Adapter Motor Shaft Collet / 5/16-24 Output Shaft. / Prop Adapter to Fit Standard Size Propellers onto a 6mm Motor Shaft. / / FEATURES: Large shaft size for Brushless (or Brushed) motors with smooth / (non-threaded) shafts / / INCLUDES: One prop adapter / One prop washer / One 5/16-24 prop nut / / REQUIRES: Tightening the prop nut to compress the prop adapter onto the motor / shaft / / SPECS: Total length: 1.72" (44mm) / Diameter of drive washer and prop washer: 1.2" (30mm) / / rmb 12-02-06 / ir/jxs