Tokyo Marui Micro Pro Sight 
 
Plastic construction
Light weight design
Dot assists shooter to aim and shoot quicker and more accurate
Dot sight provides better field of view
2 levels of red dot brightness adjustment
Optic can be zeroed (dot matches where the BB hit the target)
Package includes hard sight cover
Optic powered by ONE CR2032 battery
Attach to 20mm Picatinny rail or pistol sight mount