The Tri adapter connects (3) of our Show Off Lighting interior showcase light kits creating a triple kit. By attaching the Tri adapter you can combine (3) showcase lights and minimize the wiring. You can use this Tri adapter creating a triple kit for our 11" up to 18" LED interior showcase lights. Please note these can not be used with the 22", 28", 30" or 39.5" LED interior showcase lighting kits.