The Orient Express Train Horn DD series, (direct drive) is especially designed for vehicle owners that want the powerful sound of a train horn but have limited open space in the engine compartment. Included in the kit is Wolo's new heavy-duty compressor which is maintenance free, No high pressure on-board air tank system is required. There are two models to chose from, either three (3) or four (4) trumpets. Both models are constructed of brass which is triple chrome plated. Kit contains relay, hose and mounting hardware.