This is a spool holder that uses a 55 mm printed bearing to roll the spool, and also has a filament guider which slides along the x direction, stopping the filament from slacking outside the spool and tangling itself thus ruining your print. easy disassembly and assembly assembly guide, step 1: fit spool inside base. step 2: slide roller shaft through roller hole on base and through spool. step 3: fit 3D printed bearing into both roller shaft and base hole. step 4: fit filament guide on guide rail. step 5: fit guide rail on base. step 6: enjoy tangle free prints.