#6: P320-XTEN Launch SIG SAUER took P320 to the power of 10 with the introduction of the P320-XTEN featuring all the performance and reliability of the P320 chambered in the very formidable 10mm caliber. The SIG SAUER P320-XTEN is a striker-fired pistol featuring a polymer XSERIES 10mm / 45 AUTO grip module, a 5” Bull Barrel, flat XSERIES trigger with a 90-degree break, Nitron finished stainless steel optics ready slide compatible with a ROMEO2 and RMR optic with front and rear serrations, and XRAY3 Day/Night sights. The P320-XTEN ships with (2) 15round steel magazines and is optimized for use with the SIG SAUER Electro-Optics ROMEO2 open reflex red dot sight.