The unique Peephole Reverser was developed to assist law enforcement officers assess potential threats or activity behind dwelling doors. It's quick and simple to deploy - just place the unit's smaller end over the peephole and you can look into the room without alerting anyone inside. Its special lens system actually negates the peephole's lenses, allowing the user to view directly into the room. Compatible with most common peepholes used on apartments and homes in the U.S. Weatherproof composite casing and high quality custom-designed precision ground glass lenses. Carrying pouch included. Length: 2.7". Weight: 1.5 oz.