Premium-quality DC Plug and Receptacle. The patented Marinco® ConnectPro® Plug and Receptacle features unique locking blades with the industry's largest surface-area for maximum surface contact and electrical conductivity. ConnectPro® connections are weather resistant. The marine-grade design includes corrosion resistant, plated-brass electrical components, and a watertight sealing cap. The plug's ergonomic, soft-contoured grip allows easy hook-up and blade alignment. An O-ring seals out moisture while plugged into the receptacle. The receptacle has Marinco's exclusive Perma-Lock terminals, meaning they virtually never need to be retightened .