BQLZR Red Upgrade Aluminum Alloy Shock Absorbers 106004 90mm Length for HSP RC1:10 Off-road Car Pack of 2 Spring density from the density to ensure wide stretch not twisted. Can be rotated to adjust the spring stiffness. Note:To avoid the oil flowing out from oil container, please tighten the screw cap by tool. A great choice for simulation and short shock absorbers,Wheels down body but smooth fixed. Shock absorber diameter: 17 mm/0.67"