The highest quality recoil springs from ISMI offered in 12.5lbs, 14lbs, 15lbs, and 16lbs. Will work with our 1911 spring guide rods to tune your recoil system to the load and the feel you prefer.  These work with 4.5" and 5.25" XDM models and 5" XD models, if you are using it on a 4" XD model you will need to trim your springs. Also fits full size Springer Precision Sig P320 and P320 X5 1911 guide rods.