Traxxas optional GTX springs let you tune your X-Maxx for different conditions. The higher the spring rate, the stiffer the spring. Stock X-Maxx spring rate is 1.055. Sold in pairs. Use Traxxas stock and hop-up replacement parts to get the most out of your Traxxas RTR vehicles. This product is made from high quality materials and designed for long-lasting performance. This is replacement hardware for use on Traxxas vehicles; consult your user's manual for exact parts listings.