Eibach Spring Rubber - Durometer 80 (Yellow)Used to add progressive rate to your linear race spring, Four different durometers (60D 90D) available, Fits springs with 2. 5" to 3. 0" inside diameter. Four different Spring Rubber durometers (50D 90D) available for desired rate tuning. Spring Rubbers are used to add progressive rate to your linear race spring. Adds approximately 1. 5" of solid height to your spring. Fits springs with 2. 5" to 3. 0" inside diameters. Made in the U. S. A. and sold