A filament stopper for your dry-box. Meant to stop your filament from unwinding back into the box. Use double stick tape or glue to fasten it to the outside of the box. It has ports on the input and the output to fit PTFE tubing to completely enclose your filament all the way to the machine. I printed this with a 0.6mm nozzle though a 0.4 or 0.2 would be better for the holes fitment. The built-in supports colored yellow are meant to be removed.