Holosun Technologies 407K-X2 Green Dot, Black Color, Side Battery, 6 MOA Dot HE407K-GR X2 The HE407K-GR X2 is an open reflex optical sight designed for subcompact pistol applications. It improves on the previous version by adding Lock Mode, which was first introduced in their 2018 LEM pistol optic models. Lock Mode, when activated, locks the buttons, preventing inadvertent setting changes. Additional features include Holosun's Green 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.