Filament Spool Roller for 2020 Aluminum Extrusion

My FolgerTech 2020 just has a 2020 extruded aluminum bar on which the filament spool rolls. There's quite a lot of resistance to the spool rolling and my extruder was working pretty hard to pull filament off the roll. I designed a bearing which slots over the extruded aluminum and allows the spool to roll freely. The outside roller has a step in it to fit against the edge of the roller so you need two of these rollers for each spool.

I used two 4-40 x 3/8" pan head screws, two 4-40 nuts, and