Door viewer designed with both safety and functionality in mind, All type door viewer casings can be fabricated from solid brass, zinc alloy, aluminum alloy. All door viewers are adjustable and designed for doors ranging in thickness from 22mm to 130mm. 200 degree angle door viewers will give you the advantage of knowing who is at your door before you have to open it. Each viewer features specially constructed exterior glass to prevent scratching, a 200 degree field of vision, an interior shutter and easy installation (simply drill a hole in the door and tighten the viewer into place). In all, Using our door viewers is a simple and effective way to increase your home security.