Harmonic Gear Drive Reducer Small Strain Wave Gearbox Gearbox 100:1 Rotary Reduction Actuator, Fits Nema 17 Stepper Motor (Flange Output)

The product quality is good, works like a charm. I haven't got time to test its accuracy though, will update once I have time. But a few warnings for future buyers since this product doesn't come with any handbook, while the images on this web page are all information seller provides. I don't mind to share what I learnt so far:1/ there're 4 missing screws, 2 M3 and 2 M4. If you'd like to have it work out of the box, prepare your own screws or contact seller beforehand2/ during assembly, make sure of the right position, i.e. 15.35+-0.02mm on the 3rd product image, you don't want to destroy the wave generator3/ during assembly, DO NOT USE FORCE, it's harmonic reducer, rotate wave generator slightly to find the right angle to combine the 2 parts. You may lose its precision otherwise

Hard to find a strain wave gearbox for NEMA17 at this price. Working well with plenty of torque, no discernable backlash (I have not done any precision measurements). A bit of roughness if I backdrive it, but this is not a problem for my application.The bit of gear grease it comes with was a handy addition. Overall I'm happy with it.