This shock absorber is fitted with a chrome plated helper spring. Most often used on Bajas, buggies and trikes. The lower spring seat is adjustable to give a small amount of tension adjustment to firm up the suspension. A C-spanner is included for making adjustments. The length of these shocks is: Extended 423mm, collapsed 272mm. It is very important to fit the correct length shocks to a lowered vehicle. There must be at least 50mm of upward and downward travel from the normal ride height. To ascertain what length you require you must measure the distance between the shock mountings on your vehicle after you have removed the existing shock. This must be done with the vehicle on its road wheels (not on a jack). Once you have measured you need to check it against the shock absorbers we list.