Manley H Tuff H Beam Connecting RodsManley "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 3 8" ARP 2000 for the H Beam and H Tuff and 3 8" ARP