Ok , Allen w ebay,Plazmaman,Performance springs,Rapid springs and most likely but only a guess is intune springs. As far as I know Atomic source his own and crow springs do their own. Gaz is the only one to have a failure that I know of in those springs but others have had failures with most other brands as well . Havent heard of Nizpro springs failing, but just going soft and loosing seat pressure mind you that was a while ago and not heard anything for a while.