Iridescent colour Medium: 3/8" Caps x 3/8”Posts (10 mm x 6 mm) Okay, we've made this rivet inserting thing WAY too easy for you now. Chicago screws are like rivets, but no setting tools required. Simply punch a hole (3/16" or 5 mm) through all of your layers, pop the front and back through the hole, and screw together. Done! Recommended for thicknesses of 1/4" (6 mm) and slightly thicker. Note: Use "Loctite" to secure if needed.