We purchased this unit from a Business Closing sale. It was going to be used on a prototype project, but they never got to that. This gearbox speed reducer runs smooth and whisper quiet. It's final rpm is 65.5 and it has a Thru Hole diameter of 0.700" or just under 18mm? . We have the Factory Right angle shaft. For an extra $40.00 it has collars and its final 6.75" long shaft is 1.0" diameter. Our in-house electrician wired it 230v 3ph and ensured it's a  perfect runner. We removed the electrical Box, just to show it was temporarily wired with 4 foot cord, but they never used it..  Message with any questions. We guarantee this perfect shape motor. We do accept  returns but buyer is responsible for shipping.