... ,21,3/4" x 3/4"19.1mm x 19.1mm16,17,18,19,20,211" x 1/2"25.4mm x 12.7mm16,17 ... ,18,19,20,211-1/2" x 1-1/2"38mm ... x 38mm14,15,16,17,18,191" x 2"25.4mm x 50.8mm14,15,162 ... " x 2"50.8mm x 50.8mm12,13,14,15,16Galvanized ... ,21 3/4" x 3/4" 19mm x 19mm 16,17,18,19,20,21 1" x 1" 25.4mm x 25.4mm 15,16,17 ...