Specifically designed valving for swing arm dragsters, this shock is a mono-tube gas pressure design that allows a larger piston for the best stability during those really high hp launches. 4" stroke shock comes with coil-over hardware for a 2 1/2" or 2 5/8" i.d. x 8" tall spring sold separately. Additional specifications on this shocks length can be seen by clicking on the "More Details" box below.