S&W Race Cars' PRO-500 SERIES round tube frames are made of 4130 chrome moly tubing. The chrome moly frame utilizes 4130 brackets. Each frame arrives at your door completely jig-welded, with the Laser/Link 4-link mounts and upper shock crossmember fully installed. PRO-500 SERIES Round Tube rear frames are available in 22, 24", 26", and ...