The unique Peephole Reverser viewing device was developed to assist law enforcement officers assess potential threats and view real-time activity behind a door when the door has a peephole. This newly-updated and improved version of one of our most popular products provides a clear, discreet view into the room through a door's peephole. Its special lens system is engineered to negate the effects of the peephole's lenses, thereby allowing the user to see directly into the room. Effective on all major brands of standard door peepholes used on apartment, hotel, and residential doors. Length: 2.8". Weight: 2.2 oz. Field-of-view: 15 degrees.