Manley steel H-beam connecting rods are made from forged 4340 steel alloy. They're packed full of performance features, such as a compact uniform-grain structure for ultimate strength, full machining, stress relieving, and magnafluxing. The wrist pin and big end bores are honed to a +/-.0002 in. tolerance, and the wrist pins get a bronze alloy bushing. These units include cap screw ARP 8740 alloy rod bolts, and each rod set is weight-matched to within 2 grams.