AFCO aluminum, mono-tube design, 9" stroke, big body 2.17" outside diameter, coil-over style (use 20135 kit), non-adjustable valving, user serviceable. 4 valve on compression and 6 valve on rebound. Fine tuning by adjusting gas pressure by Schrader valve, for chassis stability and driver feel. Longer style (D) shaft .Compressed length 15.53", extended 24.47"