New F999b Super Sensitive Listen Thru-wall Contact/probe Microphone Amplifier System HIGHEST SENSITIVE LISTEN THROUGH WALL / CEILING CONTACT & PROBE MICROPHONE SET THIS IS A PRIVATE LISTING DUE TO THE NATURE OF THIS PRODUCT. YOU CAN PURCHASE THIS PRODUCT AND IT WILL NOT SHOW UP ON YOUR FEEDBACK PROFILE. Penetrable surfaces: Cement, Metal, Wood, Iron, Glass, Plastic, Brick Working time: Continuos monitoring up to 24 hours Headphone output: 3.5mm stereo @ 250mW Four audio channel: 1200Hz, 800Hz, 200Hz Maximum gain amplification: 20000 times Battery type: 3.7v lithium battery Microphone sensitivity: -70db Current consumption: 10mA Record line output: 2.5mm stereo Jack socket Battery capacity: 250mA