Sig Sauer P320, P250, P290 Magazine Catch Spring. Manufactured from quality steel, this OEM factory standard magazine catch spring is for the Sig Sauer P320, P250, and P290 pistol systems chambered in various calibers such as .45 ACP, 9mm, .40 S&W, .357 SIG, .380 Auto, and .22 LR. Once installed, this component functions by retaining and releasing tension to the mag catch during operation. This part is perfect as a spare, immediate replacement, or for the next workshop project.