imported natural rubber is used as the rubber material: the steel plate has been specially treated so the adhesion between the rubber and the steel plate far exceeds the stipulation in national standard. the hardness of the rubber is between Shore 55-70A. the shock absorbers with different hardness should be selected for different models. the absorbers are suitable for various single steel wheels, double steel wheel, vibration rollers, rammer type rollers and rubbish vibration roller. the warranty is 12 months, and we promise good price.