This is a hook to hold headphones. It fits onto a shelf of 18.5mm thickness. Print both halves and use short lengths of 1.75mm filament as pins in the holes to marry them together perfectly then glue. You may be able to scale the model to fit your shelving but bear in mind that this will affect the size of the holes for the filament locating pins. The logo shown on the photos is not on the files for this object.