The brushless motor is special one for the electirc helicopter 450 class, it has the best performance for 3D flying.It will be your best choice the 450 calss helicopter.No. From cells: 3-4x Li-PolyRPM / V: 4000Max.efficiency current: 8-10.5 ONE (more than the 75%)No load current / 10 V: 0.5 ONCurrent capacity: 40 A / 60 sRecomended model weight: 450 class Ele. Heli.Recomended prop without gear: 6 inch-8 inchColour:GreenMaterial:metalSize:Shaft diameter: 3.17mmDimensions: 31x29mmPackage Contents:2 x motorOnly the above package content, other products are not included.Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.