The Eibach ERS Formula spring with a 36mm inner diameter is a precision coil intended for coilover assemblies that require a 36mm I.D. It’s part of Eibach’s ERS family, noted for series production processes that yield linear spring characteristics, low tolerances, and consistent quality. The description stresses manufacturing repeatability and spring behavior predictability for suspension builders and tuners.
Eibach Formula Spring - 36mm I.D.