"This box is large and bulky. It fits smalls and butterfly types easily, but larges and sticks will not. For M4/M16 lovers, this is just large enough that if put it on the top rail, it will block you from using iron sights. You will need a rail riser to use optics with this, or an optic with a built in riser. On the side, it will prevent you from aiming through window slits. The back will not come off though, so your battery will be stored, but the rail mount screw will become wobbly fast. Finally, if you use a small type, the battery will bounce and move around in the inside. Would recommend paying a few bucks more for one with a lower profile, and nicer look, but it will work well enough if needed."