Double Flare > 4 gauge ~ 5mm > 2 gauge ~ 6mm > 1 gauge ~ 7mm > 0 gauge ~ 8mm > 00 gauge ~ 9.5mm > 3/4 inch ~ 19mm > 1 inch ~ 25mm > 1-1/4 inch ~ 32mm > 1-1/2 inch ~ 38mm > 1-7/8 inch ~ 48mm