Material: ZINC PLATED STEEL Assembled Product Length: 0.75" Fastener Drive Type: ROBERTSON Fastener Diameter (Imperial): #8 Fastener Length (Imperial): 0.75" Fastener Length (Metric): 19.05 MM Fastener Diameter (Metric): N/A . Square socket drive • Used to fasten metal to metal, metal to wood and other types of materials, with machine tapped threads or nuts, where disassembly may be required or where a more secure clamping of parts is desired