Front Round Base Coil Spring Boosters Material: NR+RR Size: 6" OD, 4" ... , 1.5"Thickness Hardness: 60-70 Shore A Front Round Base Coil Spring Boosters Material: NR+RRSize: 6" OD, 4" ID ... : Black colorTemperature Rage: -40°C to +120°C. Front Round Base Coil Spring Boosters/Bumpers,Auto rubber accessories