These Eibach ERS Tender springs are meant to be used with a much stiffer linear rate main spring. They are wound from flat wire so that when loaded, the springs compress until they completely bind up into the shape of a small disc. The Eibach ERS Tender springs are specifically designed for use with the Eibach ERS race coil springs, allowing the suspension to work to its optimal level. Perfect for an adjustable coil over system, these Eibach ERS Tender springs offer maximum control under the harshest racing conditions.