This is the Prop Flange (hub) for the Fuji Imvac BT-50SA and BT-50SB Gas Engine This Flange attaches to the Magneto (part #51) and provides a surface on which to mount the propeller. FEATURES: Constructed of aluminum for light weight Serrated area where prop contacts ensures tight grip INCLUDES: One Prop Flange for the Fuji Imvac BT-50SA Gas Engine REQUIRES: Attaching to Magneto with three Hex Bolts (part #3) FJIG8260 Installing propeller, Prop Washer (part #1), and Bolt (part #2) FJIG8060. SPECS: Length: 2.44" (62mm) COMMENTS: As of 1/04 Fuji shortened these hubs to 52.5mm (2.07")-this will be a permanent change ADDITIONAL COMMENTS: Fuji Imvac is NOT related to the original Fuji Engines sold by MECOA. JXS 10/11/01 ir/kh updt jxs 1/21/04