POL -13″ Black OutTrack 4, disc brake conversion by Baer takes your braking performance to the next level. Works with 1964-72 A-body, 1967-69 F-body and 1968-74 X-body stock OE spindles as well asHeidts, Fatman & Ridetech 2″ drop spindles. Billet alluminum hubs come packed with Redline synthetic grease and include billet dust caps. The POL Branded Baer 4 piston T4 calipers include D.O.T. compliant dust and weather seals.