6 blade impeller Width: 7/8" (22mm) , Diameter: 2" (50.8mm)) , Shaft: .472" (12mm) , Drive: Pin / Slot. Neoprene For engine cooling. Fits Westerbeke Models: 4.0 BCD(60Hz) 4.4 BCD(60Hz) 4.4 WMD (60Hz) / 3.3 WMD (50Hz) 5.0 BCD (60Hz) /4.0 BCD (50Hz) 5.0 BCDA (60Hz) / 4.0 BCDA (50Hz) 5.0 BCDB (60Hz) / 4.0 BCDB (50Hz) 6.0 BCD (60Hz) /4.5 BCD (50Hz) 7.6 BTD (60Hz) / 5.7 BTD (50Hz) 7.7 WMD (60Hz) / 5.8 WMD (50Hz) 8.0 BTD (60Hz) / 6.0 BTD (50Hz) 8.0 BTDA (60Hz) / 6.0 BTDA (50Hz) 8.0 WMD (60Hz) / 6.0 WMD (50Hz) 10.0 BTD (60Hz) / 7.5 BTD (50Hz) 10.0 BTDA (60Hz) / 7.5 BTDA (50Hz) 11.0 BTD (60Hz) / 8.3 BTD (50Hz) 11.0 WMD (60Hz) / 8.3 WMD (50Hz) 12.5 BTD (60Hz) / 9.4 BTD (50Hz) 12.5 BTDA (60Hz) / 9.4 BTDA (50Hz) 12.5 BTDB (60Hz) / 9.4 BTDB (50Hz) 12.5 WMD (60Hz) / 9.4 WMD (50Hz) 15.0 BTDC (60Hz) / 12.0 BTDC (50Hz)