For Bennche Bighorn 500, 700X-HD，700, 700HD. For Massimo MSU-500, MSU-700, MSU700-4. For Massimo Alligator 500, 700, 700-4. The fan shroud basically houses the fan blades securing it in place and keeping it from damaging the other engine components that may disturb the smooth and even operation of the engine.
