I have my filament dryer/spool holder in the shelf compartment next to my printer (see pictures). so I have the PTFE Tubes running around the wooden shelf divider. as the extruder moves, the tubes would rub on the divider wall. so i decided to design this smooth protector for the tubes to slide in. It´s designed for a 16mm wide shelf wall, you can use the screw holes to fix it to a thinner wall. it will pressure fit onto around 16-17mm shelf wall thickness.