YSS Suspension-Store developed this shock absorber specificly for the linksystem commonly known as RetroRides . We have seen many builds using an unfit shock absorber, which is simply dangerous. Those shock absorbers may not be fitted in a horizontal position. The shock we developed has a separation piston in it, which ensures that the Nitro gas doesn't go sit around the damping system. The mounting point measurements, springrate and hydraulic settings are specificly developed for this system on these bikes, no other existing shock has this, so this is the only fit existing shock.