Are you taking about height adjustable coilovers? Stick with big names such as Bilstein, Tein, Koni, Sachs, Eibach, Apex, H&R, KW, etc. and you should be alright. Most ebay "non-brands" have proven to be pure junk. Many of the name brands are available as well but, as always, make sure you are buying from a reputable dealer/seller.