Optimised response characteristics and large reserves generate very secure ground grip combined with high levels of comfort. These suspension struts with reservoirs permit infinite adjustment of the spring pre-tensioning, a 22-position adjustment of the traction level and a 22-position adjustment of the pressure level, split between the high and low speed range (short surface irregularities / long strut movements e.g. on traffic bump). The reservoir with pressure level adjustment is located directly on the suspension strut on the 632/642 and 633/643 versions, on the 631/641 versions it is connected with a hose and can be fitted flexibly. The classic version complies with what is "normal" but has a black spring instead of a blue one. Approval: with operating licence (Germany only). As an option, the suspension struts can also be ordered at extra cost with height adjustment (629) or hydraulic spring pre-tensioning (625) - a combination of the two is unfortunately not possible here!! Repairs and maintenance are possible via Wilbers Products.