PSM 6KG MAX Super Light Linear Spring 61mmID 180mm Length (PAIR)Parts Shop Max 6KG MAX Super Light Linear Spring 61mmID 180mm Length Listing is for: 1x Pair of Coilover springs Springs shorter than 6" must use helper springs sold separately. If you are putting 20KG plus on a McPherson strut car like S13 & BRZ, you will need helper springs. This will make sure you're not topping out your shocks, which will damage the shock. However, 20KG+ can be used on a big body Lexus and other double wishbone cars without helper