Ultimate M90 Spring
M90 Spring van het merk Ultimate.
The Ultimate springs are named M100, M110 etc. according to their expected tension in meters per second ? measured when using a 0.20gr BB and a 300mm long barrel. In turn, a M110 spring would give 110 m/s. To convert to feet per second (fps) simply multiply by 3,28, e.g.: M120 ? 120ms/394fps.