UNF Self Colour Steel Castle Nuts Thread - UNF Material - Steel. Grade - Grade 5 High Tensile. ABCD 3/8" 9/16" 13/32" 24 7/16" 11/16" 3/8" 20 1/2" 3/4" 0.56" 20 5/8" 15/16" 23/32" 18 Please Note: Specifications given are intended as a guide... £0.97 (Inc. VAT) £0.81 (Ex. VAT) Choose Options Compare