*New advanced battery technology offers up to 3000 hours on bright setting and up to 40 hours on low setting on a 2032 battery*The biggest gun sight on the market! Real size. 2.2"e;L x 1.7"e;W x 1.7"e;H. Gives up to two times more window than other micro red dots. *The red dot does not turn off automatically. It stays on until manually turned off.he 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.