The size of the red dot is about 30% longer than other red dots, the window is also bigger. Therefore, it will NOT fit some Optic Ready handgun model that will keep the rear sight to co-witness the red dot, such as Glock Mos. The size of this red dot does not sit in to the pre-cut. It only fits the mounting plate replace the rear sight on the top of slide(not in the pre-cut). It fit Doctor/Vortex Venom footprint /screw pattern. Model: RD3-015. Every time you turn on the dot it stays the same brightness level last time it was turned off. The lowest setting is invisible by human eye that is for using with a Night Vision. Come with a mounting plate for picatinny rail. Additional mounting plates for hunguns sells separately. Can also be used with a long range rifle scope for that perfect Backup System. Ade Advanced Optics first made its appearance in the firearms accessory industry by doing private label production for several major manufacturers and retailers. During this period, Ade Advanced Optics began receiving requests from numerous customers for access to the affordable, high quality products that Ade Advanced Optics was capable of producing. By soliciting feedback from both clients and end users, Ade Advanced Optics was able to overcome the challenges a new company often faces when entering a global market and industry, especially one as competitive as the shooting, hunting, and outdoors industry.