CIRCULAR SIZE 21 4WAY SKT; Military Specification:MIL-DTL-38999 Series III; Circular Connector Shell Style:Straight Plug; No. of Contacts:4Contacts; Circular Contact Type:Crimp Socket - Contacts Not Supplied; Coupling Style:Threaded; Insert Arrangement:21-75; Connector Body Material:Stainless Steel Body; Connector Body Plating:Passivated; Contact Material:Copper Alloy; Contact Plating:Gold; Insert Rotation:A; Service Class:Corrosion Resistant EMI Firewall; Product Range:MIL-DTL-38999 Series III