Rather than like the majority of open sights in the market that have two separate upper pieces of chassis that hold the lens in place with the tendency of the lens cracking, the OS11 upper body is constructed by a whole piece of aluminum that can withstand thousands of rounds without any problem. The unique design of battery chamber, located at right side, allows you to change your battery effortlessly and quickly without dismounting your sight and losing your zero. The illumination switch buttons is conveniently located on left side and can be simply turned on and off by holding on the + button. Furthermore, you can mount the sight on certain selective handgun models, such as Glock, by taking off the picatinny rail mount and mounting it on the adapter plate ( you need to buy the adapter plate separately) that has been mounted on your handgun already. To remove the picatinny rail mount, just simply loosen the two top screws on the main chassis.