... BWG> In inch In metric unit(mm) 1/4" x 1/4" 6.4mm x 6.4mm 22,23,24 3/8 ... .6mm 19,20,21,22 1/2" x 1/2" 12.7mm x 12.7mm 16,17,18,19,20,21 ... 23 5/8" x 5/8" 16mm x 16mm 18,19,20,21, 3/4" x 3/4" 19.1mm x 19.1mm 16 ... ,17,18,19,20,21 1" x 1/2" 25.4mm x 12.7mm 16,17,18,19,20,21 ... 1-1/2" x 1-1/2" 38mm x 38mm 14,15,16,17,18,19 1 ... " x 2" 25.4mm x 50.8mm 14,15,16 2" x 2" 50.8mm x 50.8mm 12,13 ...