Product Description-------------------1.Works on wooden walls， doors， windows， steel plates， etc.2.Highly Sensitive， carefully adjust audio slowly， as not to cause discomfort to your ear-buds3.This product is being sold as an investigative tools for law enforcement or licensed investigators.Specification-------------(1) Primary Function: Audio Wall ear listens(2) Materials: Molded Plastic with Internal Sound Amplifier-Color: Black-Onboard Buttons/Slots:-- 3.5mm Earphone Jack-- USB IN-- Sensor-- ON/OFF Switch Button with volume Dial(3) Power: Built In Rechargeable Battery(4) Dimensions: L:43 x Diameter:36 (mm) Package Included:-----------------1x wall ear listens1x Earphones1x USB Cable1x Power Charger