The Ultimate range of springs was developed by Eric Grauffel and his team to improve your shooting sensation. These springs are ideal for shooting in competition, they will guarantee lightness and performance. The Recoil Spring Ultimate is suitable for all types of handling and ammunitions. Eric recommends an 11lb spring for Production Optic to preserve your optics, as well as in Cal.40SW and 9mm major. This spring is compatible with all the CZ 75 type pistols.