This is the GWS EPS-400C Electric Power System.FEATURES: Pre mounted GWS EM400 Ball Bearing motor with 3"(76mm) 18 gauge leads and a pin connector Grey plastic motor and gear housing 2.14:1 drive ratio 1??" Black plastic spinner with adapter to accept 2 blade propsINCLUDES: One pre-assembled 400 motor, 2.14:1 geardrive, 1??" spinner systemREQUIRES: 7.2V-8.4V battery (600-1000 NiCd) (730-200 NiMH) GWSQ2009 8x4 prop (Slo Flyer) GWSQ2018 9x4.7 prop (Slo Flyer)SPECS: Diameter of motor case: 1.1" (27.7mm) Length of case behind spinner: .87" (22mm) Distance from spinner to case: .80" (20.3mm) Distance from pinion to prop shaft: .70" (17.6mm) Length from top of case to bottom of case: 1.8" (47mm) Weight: 3.3oz (95g)GWSPart GWSEPS-400C-AS/BB