After 6 months of trial and error Mad Bull released their high performance (and colorful) AEG upgrade springs. The spring is not painted but rather hard coated to preserve the integrity of the spring. Mad Bull tested their springs over 100,000 times to ensure the quality of design and the overall durability of the spring. After 100,000 "punches" the length and force were still consistent. It's not just a spring, it's a Mad Bull Spring... Other features: Consistent >100000 shotsl Non-liner design (calculated) Color coating to reduce effects from environment Designed & Made by experienced engineers. Premium quality German piano wire