Sig Sauer P320 Rear Night Sight Base, #8. Manufactured from quality steel, this OEM factory standard night style rear sight #8 assembly base is for the Sig Sauer P320 pistol system chambered in .45 ACP, 9mm, .40 S&W, .357 SIG, .380 Auto, and .22 LR. Once installed, this component functions by providing the operator with quick and easy target acquisition in most environments including night, low-light, and day . Pair this piece up with your favorite slide and sight as an upgrade, replacement, or for your next workshop project.