Mini 8 x 20mm Portable Pocket Adjustable Monocular Telescope For Outdoor Sports Hiking Bird Watching Objective lens diameter: 20 mm Dimensions: 7.5*3.8*3.8cm Material: Aluminum Please don't look at the sun absolutely. If you look at the sun, your eyes may be ache and blind sometimes Never attempt to clean your monocular internally or try to take it apart.