This new brake tee is a simple & easy way to add a pressure activated brake light switch on your vehicle. The tee is designed for use with 3/16" hardline & has (3) 3/8"-24 inverted flare female ports and one 1/8" NPT port for the brake light switch (use with switch part # 100186ERL). Mount the tee anywhere you would normally branch off to the front or rear brakes (using the 7/16" mounting hole). Brass construction.