This the Ultimate Cooling Machine! With wide variety of tapered shrouds, designed to fit almost every radiator on the market. (Tapered shroud guarantees maximum air flow through all the fins of the radiator). With only 2 5/8” clearance needed it is simply the slimmest, biggest air flowing fan & shroud setting on the market. There is a patent for this 17” blade to be the quietest one. The two speed motor on these fans are developed for Humvees. So they are tough and durable.