Made In USA. Melling recommends new rocker arm bolts with every engine rebuild. Old bolts are subject to metal failure, bolt stretching, and worn threads. Bolts also tend to be lost or damaged during the rebuilding process. There is also a danger of metal cracking when the old rocker arm bolt is removed from the head. Melling rocker arm bolts are manufactured to high quality and material standards. Using new rocker arm bolts assures proper installation and valve train adjustment.