Plugs, Tunnels & More > Single Flare > 10 gauge ~ 2.5mm > 8 gauge - 3mm > 6 gauge ~ 4mm > 2 gauge ~ 6mm > 1 gauge ~ 7mm > 0 gauge ~ 8mm > 1-1/8 inch ~ 28.5mm > 1-1/2 inch ~ 38mm > 1-5/8 inch ~ 41mm