Smooth running servo, very powerful. Position tracking however is a bit on the low side even after correct tuning(software makes it easy though). Use 2:1 belt timing pulleys with those to increase actual precision of positioning, then it's worth it. If not you'll be in the 0.03mm postion error range, which isn't very good. Seller is great, shipment was returned to them due to a problem and they resent it immediately.