The H Series Transformer is an internal (non waterproof) 12 volt lighting transformer designed to operate at the lowest possible temperature. Due to its low profile the H Series Transformer fit through a 63mm (2 1/2") diameter hole. Wiring is made much easier by the use of a 25 amp (6mm or 1/4" diameter terminal) connector-block, which facilitates quick and easy wire-in and loop-out connections. For interior use only.