Chicago Screws: Medium: 3/8" Caps x 1/4" Posts (10 mm x 6 mm) - Gold - 50 PackChicago screws are like rivets, but no setting tools required. Use a leather punch to make 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) (Medium) and slightly thicker, and 3 8" (10 mm) for Large. Note: Use "Loctite" to secure if needed. Sold in Packs of 50 Choose from: Small: 3 8" Caps x 3 16" Posts (10 mm x 4 mm) Medium: 3 8" Caps x 1 4"