Holosun 507K X2 [red]This red dot uses the Holosun K series footprint standard. The HS507K X2 is an open reflex optical sight designed for concealed carry pistol applications. The X2 Series pistol optics feature two improvements. First is the addition of Lock Mode from our 2018 2019 LE pistol optic models. Lock Mode, when activated, locks the buttons preventing inadvertent setting changes. Second, the buttons have been redesigned to compliment the Lock Mode by placing