Holosun HS507K Compact Pistol Reflex Red Dot Sight 2x 0.58 x 0.77 in MOA Red ACSS Vulcan Reticle Black HS507K-X2-ACSS. The Holosun HS507K X2 improves on the previous version by adding Lock Mode which was first introduced in our 2018 LEM pistol optic...