Chambered in 40 auto this barrel is meant to fit with either the P320 or P250 Compact models. Barrels can be replaced easily and conveniently by simply ensuring the firearm is unloaded, removing the slide from the receiver and grip module, and sliding out the existing barrel.
Sig Sauer BBLMODC40 P320 Compact40 S&W 3.90″ Black Nitron for Sig P320 & P250 Compact Models