3-520140-4 is an Ultra-Fast fully insulated FASTON receptacle terminal designed for quick-connect electrical connections. This terminal accommodates 12-10 AWG wire and features a phosphor bronze base material with tin plating for reliable conductivity and corrosion resistance. The receptacle is designed for 0.51 x 0.250 inch mating tabs and includes a translucent yellow nylon housing (UL 94 V-2 rated) that allows visual inspection of the crimp and wire brush. The one-piece fully insulated design helps prevent shock and short hazards while providing funnel wire entry and wire stop features. Common applications include automotive, appliance, and industrial equipment where secure, insulated quick-connect terminations are required.