Sonora 4000 FB Spinning Reel Propulsion line management system: Propulsion spool Lip, Power Roller III, S-Arm Cam Varispeed Oscillation Shielded stainless steel ball bearings Lightweight Graphite Frame, Sideplate & Rotor Cold Forged Aluminum Spool Lightweight Spinning Reel features propulsion line management system helps provide longer casting distance while preventing backlash. Features varispeed oscillation technology. Shielded stainless steel ball bearings.