The Mahle PowerPak was designed as a completely finished drop in piston assembly. Other than filling the included performance ring set, everything is done for you. Designed from 80+ years of piston manufacturing for everything from OEM to Formula1, only the best technology is used to make these pistons. They are forged from 4032 aluminum alloys to suite specific needs for strength and durability. Some combinations offered in PowerPak Plus. Forced Pin Oiling is used for increased wrist pin lubrication. Pin bores are CNC precision machined. .927" High Quality Steel Wrist Pin (118g), Performance 1.0, 1.0, 2.0mm rings, and Race Proven Round Wire Locks are included.