At first glance the ZRTS spring was significantly shorter which kinda concerned me. But after installing I realized that the spring was also much stiffer which enabled it to function properly. I've only put about 50 rds through it with the new spring and it has worked flawlessly. The original spring also worked perfectly but the ZRTS makes the gun feel a bit smoother. Definitely worth 9 bucks! I will purchase again if/when I ever need a new one! Excellent shipping also!