Using this AimPoint Red Dot Reflex Sight is easy. First, insert the CR2032 battery. You can then adjust the settings according to your needs, choosing from the 4 night - vision compatible settings or 8 daylight settings. The 2 MOA dot size helps you aim precisely. When not in use, switch it to the Off position. As it's submersible up to 25 meters, it can be used in wet conditions, but make sure to dry it thoroughly after exposure to water. Keep the flip - up lens covers on when the sight is not in use to protect the lenses. Replace the battery when it runs out after about 50,000 hours of continuous operation. For best performance, clean the lenses gently with a soft, dry cloth.