The MIL-C-38999 Series I connector series is a bayonet coupling sub miniature configuration, with high contact density, ideal for smaller wire gauge applications. These Series 1 environmental resistant connectors are 100% "scoop proof". The connectors are available in nine shell sizes, with five receptacle configurations and standard RFI plugs. There are 54 insert arrangements available, utilising 3 to 128 contacts. Contacts are 22D, 20, 16 and 12 gauge (and combinations); terminating wire sizes 28 through 12 gauge. The hard plastic socket interface features the chamfered conical entry that aids in the proper mating of contacts. The fluorosilicone interfacial seal has conical risers around each pin contact that compress into the socket interface, assuring the seal of the mating surface. Cadmium over nickel and electro less nickel finishes are available for aluminium shells. Polarisation is machined into the shell (Locksmith Keying).