Wire grommet for small cables, ie. network cables, 2 wire power cords, etc. Hole in the counter/desk needs to be 1.25"The unit is made in 3 pieces without Raft or Support. All three parts fit together without any glue with my printers. I made them fit tight together but if your printer is lighter on filament (Feed Rate), glue would be fine. I created mine with PLA just to insure they print flat. Also used .3mm layer height and 10% fill to print fast, (less than 15 minutes for each part.)