The adjustable angle is an innovative design of this bird watching mirror, which complements ordinary bird watching mirrors. The larger the aperture, the greater the luminous flux, and the brighter the imaging. It is nitrogen filled, waterproof, and anti fogging. All light passing through the contact surface between glass and air is treated with multiple layers of coating. Multi layer coating effectively improves the transmittance, making the imaging clearer and brighter. The eyepiece and objective are both made of FMC full surface multi-layer anti reflective green film, with clear imaging and high color saturation. Easily cope with various humid environments, prevent fogging and mold formation inside the lenses, and extend the lifespan of the telescope.