FSO Oil Reservoirs are used to enhance the performance of the FSO series clutch when used as a backstop on the high speed shaft or intermediate shaft of a reducer, or as holdbacks on the head shaft of a conveyor. The oil reservoir is made from an aluminum casting with cooling fins to permit free oil flow between clutch and reservoir providing increased cooling capacity and increased backstop life. When specified together with an FSO series clutch, the combination is designated as an HSB model. They are available in sizes 400 through 1027.