This is a Wire Grommet printed out of TPU to block the light that escapes from your light box. Makes for a finer finished product. This one fits some of the bigger holes I've encountered 21mm x 10.5mm. Has a 4mm hole for the wire. You can also resize in slicer. Print with 5% Infill so you can cut one end of the grommet so the wire can slip into it. then push & glue it in place.