This is intended to be an extension to the very good filament buffer that EagleEI did as seen here. I use that buffer but originally found it to be too small (no fault of EagleEI there - it's just the size of the Prusa plater is all.) So I designed these extension to allow the filament more room to rest. They work well and the filament is no longer creeping back into the MMU causing issues. I hope they help.