Such a small thing, but it prevents so much misery loading the filament. These inserts fit inside the following housing: http://www.thingiverse.com/thing:325551 This is not a remix, as much as it is an extra piece to an already good design.. These inserts prevent the filament from getting stuck on the lip of the housing.PLA, 20%, .2 layer One picture shows the insert and the other without, If your filament gets stuck on that lip inside the housing, then you need this insert.I drilled mine out with a 1/8" bit which gives the extra room for unloading filament that got a little messed up in the extruder.