... surface type is available all size is available with different materials:Metric, Unified; Steel,Brass, Aluminium ... 0.01, length from 0.3 to 180mm with tolerance to +/-0.02, other centerless grinding tolerance ... 0.01, length from 0.3 to 180mm with tolerance to +/-0.02, other centerless grinding tolerance ... B 18.2.2 details informationFastener remains flush with both sides in sheets as thin as .060"/1.5mm ...