*High quality materials: red dot sight is made of strong and lightweight anodized aircraft aluminum alloy*pistol red dot can be folded into a flat surface when you are not in use*The 22MMX16MM diameter multi-layer coated lens promotes maximum light transmission and wear resistance while reducing glare, and provides a wide field of view to help you increase accuracy and shoot targets quickly.You can take a picture of this red dot with your phone in medium brightness. If you see the full dot in the photo, you can infer that you have astigmatism.