The SIG Sauer P320 Carry 40sw Contrast Sights, is a striker fired pistol with a smooth and consistent trigger pull. The P320 pistol is modular and has a striker fired interchangeable trigger group that can be removed from the pistol and installed into a SIG Caliber X-Change kit (sold separately). Allowing you to change calibers and or pistol sizes while only having one serialized trigger group.