All 17 series motors have 24 slot stators and 8 poles rotorsMax RPM: 35,000Case Diameter: 1.7″Shaft: 5mmShaft Length: .75″Mounting screws are M3Direct Drive or GearedThe 17 series is designed to full the need for a high torque motor in a smaller size than our 19 series. The 17 series feature a 24slot stator and 8 pole rotor design that has been optimized using computer aided magnetic field analysis. This gives the 17 series motors higher efficiency and power in a small light weight package. The motors all feature 5mm hardened steel shafts and 13mm ball bearings. The standard internal cooling fan makes this motor ideal for helicopters. We will be adding more versions in the next year.