The SKF Tamper-Proof Hub Cap is The SKF Tamper-Proof Hub Cap is designed to provide superior protection for your Volvo vehicle. Its outer diameter of 6.850" ensures a secure fit, while an embedded aluminum ring evenly distributes load. The molded pressure ridge improves sealing ability, and the proven center-fill vented plug-in design ensures a tight seal. The side fill plug incorporates an O-ring for extra leak protection and a magnet which traps metallic particles. The patented umbrella style valve seals keep out contaminants, providing superior protection for your vehicle. FleetPride is your First Click in Heavy Duty®.