The dice are approximately 15mm in length and width. The set screw hole is in the middle, so it's about 7.5mm. The hole diameter is about 6mm, so please check the diameter of your instrument's knob before purchasing. These are handmade, so please understand that there may be some hole misalignment, scratches, and imperfections. These cannot be attached to vintage Gretsch guitars. The holes are made for current models. A hex wrench is required. Search terms: Beatles George Harrison John Lennon Rockabilly Gibson Fender Vintage Gretsch Upright Bass Gretsch 6120 GRETSCH Rockabilly Stray Cats Brian Setzer Dice Dice Dice Knob Dice Knob