The 6-inch Tri-Clamp coil with a 1/2-inch dip tube is a 6 inch lid with 3 ports, the 2 outside ports are the input and ouput for fluid in the coils. the center port is a half inch diptube, the diptube allows to reach to the bottom of your tank. The coils are effective for cooling dow n the interior of your tanks. The coils have a 3/8" ID.