The F999B High Strength Listen Through Wall System is a professional grade acoustic leakage detector and audio monitoring kit. It operates using a highly sensitive quartz piezo crystal to pick up micro-vibrations traveling through solid barriers, amplifying those structural sounds up to 20,000 times into clear audible speech / sounds.
Listen to conversations through walls, floors, ceilings, doors, windows or other solid surfaces, ideal for security, research and investigation. Effective tool for detecting gas leaks or leaks in water pipes.
Core Technical Specifications
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Maximum Audio Amplification: 20,000x.
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Microphone Sensitivity: -70db.
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Penetrable Materials: Concrete, cement, brick, wood, iron, steel, glass, plastic, and solid pipes.
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Power & Battery: Built-in 3.7V rechargeable lithium battery providing up to 24 hours of continuous live monitoring.
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Audio Filters: 4 equalised channel modes (1200Hz, 800Hz, 200Hz, and partition/bougie monitoring) to filter out background static.
Included Dual-Sensor Hardware
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Sonde Contact Microphone: A heavy, round metal puck design. It must be placed perfectly flat against flat surfaces like doors or walls to capture low-frequency vibrations.
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Probe/Needle Microphone: A long, ultra-thin metal probe. It is engineered to insert directly into keyholes, wall cavities, cracks, or gaps for localized pinpoint detection.
Functional Inputs & Outputs
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3.5mm Headphone Jack: Connects the included earbuds for direct, real-time live monitoring.
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2.5mm Audio Record Output: A dedicated line-out terminal. It lets you connect the F999B directly to an external voice recorder to log and store captured audio securely.
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FM Transmitter Capability: Features an integrated wireless FM transmitter allowing the audio feed to be broadcasted to a separate FM radio receiver from a distance.
Safety & Operational Warnings
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⚠️ Protect Your Ears: Always lower the volume dial to zero before placing the microphone onto a wall. Shifting or sliding the contact sensor across a rough wall while listening creates harsh, immediate acoustic feedback spikes that can damage your hearing.
- ⚠️ Sensor Protection: The internal piezo sensor pin is fragile. Do not press down excessively hard or drag it across surfaces.
