MS3102R20-19P is a box mounting receptacle connector conforming to MIL-DTL-5015 specifications, featuring a lightweight environmental-resistant design with shell size 20 and 19-contact insert arrangement. The connector utilizes a neoprene grommet with low coefficient of friction for easier wire bundle threading and faster assembly, with molded webs in each wire hole providing a moisture barrier around individual wires. The shell is fabricated from high-grade aluminum alloy with cadmium plating and olive drab chromate after-treatment for corrosion resistance, while contacts are machined from copper alloy for maximum corrosion resistance and current carrying capacity. The MS-R class design incorporates an axial compression nut and grommet assembly positioned flush with the rear of the insert, achieving a low-profile assembly suitable for new design applications requiring greater reliability in a compact, lightweight form factor.