Single Flare > 12 gauge ~ 2.0mm > 6 gauge ~ 4mm > 2 gauge ~ 6mm > 0 gauge ~ 8mm > 00 gauge ~ 9.5mm > 5/8 inch ~ 16mm > 1-1/8 inch ~ 28.5mm > 1-1/2 inch ~ 38mm > 2 inches ~ 51mm