Manley ""H"" Beam connecting rods are manufactured from 4340 forgings to the same exacting standards developed and approved by our original equipment customers. There is a vast difference in quality between a Manley ""H"" Beam and the ""other"" inexpensive H-Beams on the market. Weight matched to +/- 1.5 grams. Perfectly round big and small ends. Bend and twist is tightly controlled. Cap fasteners are 7/16"" ARP 8740 for the ""H"" Beam and 7/16"" ARP 2000 for the H-Plus.