SC connectors are medium size, constant 50 Ω (also 75 Ohm) impedance units manufactured to meet MIL-C-39012 category D, Specification sheets 35 trough 43, meeting all of the mechanical and electrical requirements of the Limited Co-ordination Specification (LC Spec.) as generated by the U.S. Air Force.
Note - "SC" is basically a screw-coupling version of the "C" bayonet connector.
Connector mating is a 11/16" x 24tpi UNEF screw thread.