FSO Series FSO300-700 Backstop Cam Clutch One Way Bearing FSO300 Product Introduction The FSO, FS, and HPI 750 to 1027 series are sprag type freewheels that are self-contained, sealed, and bearing supported, using two ball bearings. Units are delivered oil or grease lubricated according to type. Based on Formsprag USA design, these units feature tall sprags with multi-radius active surfaces, specially engineered for large size freewheels to compensate for any eccentricity due