Disc brake Distribution Block and Rebuild Kit-1967-1969 Another Product by Mr. VacuumMan- Kit for rebuilding your disc brake distribution block and proportioning valve on 1967-69 Mercury Cougar and Ford Mustangs. Special square O-rings are made from EPDM (Ethylene Propylene 70 Durometer) which is designed SPECIFICALLY to withstand chemical degradation caused by prolonged exposure to brake fluid unlike Nitril. This is a North American made product.