This is a fan shroud to allow more common 25mm fans instead of the sideways 30mm blower type fan that SeeMeCNC prefer to use.  My original's bearings went and I wanted to replace it with a normal, off the shelf unit. 

This is designed for the new V3 Ball Cup Delta Arm platform, as seen here: https://www.seemecnc.com/products/rostock-max-ball-cup-delta-arm-kit

Printed mine in Polycarbonate, just be mindful of support and its requirements for your filament and printer.