Bolt stretch in the valvetrain of a DOHC application robs power by allowing the cam to lift from the head without opening the valve. Unlike the factory bolts these MMR bolts are re-usable and are made from 190,000 psi tensile strength material. Kit includes all bolts and washers to assemble a pair of cylinder heads. Recommended for all applications with upgraded springs or cams or for simply replacing the 1 time use factory bolts. Fits all 2011 - 2017 5.0/5.2 cylinder heads