Specs: . Rpm/V: 1000kv . Shaft: 3.17mm . Voltage: 2S~4S (7.4v to 14.8v) . Weight: 52g . Watts: 210w . Max Current: 21A . ESC: 30A . Suggested Prop: 8x4 (4S) ~ 10x7 (2S) . Mounting Hole Bolt Circle: 16mm or 19mm .