The HS407K X2 is an open reflex optical sight designed for subcompact pistol applications. The HS407K X2 improves on the previous version by adding Lock Mode which was first introduced in our 2018 LEM pistol optic models. Lock Mode, when activated, locks the buttons preventing inadvertent setting changes. The HS407K X2 is an open reflex optical sight designed for subcompact pistol applications. The HS407K X2 improves on the previous version by adding Lock Mode which was first introduced in our 2018 LEM pistol optic models. Lock Mode, when activated, locks the buttons preventing inadvertent setting changes. Additional features include Holosun’s Super LED with up to 50k hour battery life, a crisp 6MOA dot, and Shake Awake. The durable housing is made from 7075 Aluminum, uses Holosun’s K footprint, and houses the 1632 battery in a side-mounted tray for easy replacement when needed.