SIG SAUER P320 Full .40 S&W 14Rd Mag Black Caliber X-Change Kit (CALX-320F-40-BSS)

All parts are a perfect fit with the M17 9mm FS gun. I have a P320 M17 in 9mm but really wanted one in 40. This kit not only works perfectly with the FCU but the grip, slide and mag are also all interchangeable with each other. The illustration looks like it doesn't come with the mag release assembly but pleasantly to my surprise, it arrived with the mag release installed. I got a notification that it was available on Wednesday evening, ordered it immediately, it was shipped on Thursday and it arrived on Friday. Right out of the box, I took it out on Saturday morning and put 150 rounds of 180g TC at 1000 fps through it and they all functioned smoothly with no need for a break in period. The slide has fixed night sights installed, but no optics plate. Very happy with this kit.