These are a staple in the field of 1000W Direct Drive Hub Motors. They have been produced for a long time and MXUS makes a great product with these XF40 motors. Copied over the years from other companies, these still hold their own.

Balanced 6.5T Winding, about 1km/hr/volt. So 48V = 48km/hr with 26'' wheel. 52V fully charged is 58.8V or 58km/hr. Capable of much more power with Statorade and Hub Sinks.

Intended for 135mm rear dropouts, and freewheel gearsets.

DDR-40 1000w (mxusebikekit.com)