ORV only uses nitrogen charged gas shocks for all their kits. Though a little more money, the nitro gas shock in combination with the ORV kits provide a better ride both on and off road. By using an ORV lift kit and matching gas shocks, you optimize the suspension's capabilities giving you a better ride both on and off road. 150 PSI pressurized Nitrogen gas Internal valves-the internal orifice will rotate when the piston moves more than 2 inch automatically adjusts to make the ride as smooth as possible Twin tube construction to lower heat build up and protect the shock from off road damage. Bonded Iron 14mm piston with extra chroming-provides for a longer, rust free life. Includes polyurethane bushings. Limited lifetime warranty on the shocks.