These parts press-fit onto the bearings on the tower for the Printrbot Simple. It accomodates spools from 65mm to 90mm in width.

Note: It might look like the long rollers are sagging, but they are very rigid! The slight angle is from the way the tower piece is designed. At most, there is only a 0.6kg load per roller.

A bench vise is recommended to press the bearings in. It's a nice tight fit. Parts print good in PLA.