Work on wooden walls, doors, windows, steel plates, etc.Highly sensitive, please adjust the audio slowly and carefully to avoid discomfort to your earbuds.The audio gadget works by amplifying the vibration of audio. When people chat in the room, their voice is only a band, and according to the size of the voice they speak, the band will travel through short and long distances and be amplified and amplified by this device.Colour: Blackmaterial: metalPackage Contents:1 x Detector1 x USB Cable1 x Circular probe1 x Needle probe1 x Headphone1 x Chinese and English manualOnly the above package content, other products are not included.Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.Product Notes: Please allow a little manual errors.Due to the lighting of the photos and the difference of monitors, the pictures may not reflect the actual color of the real item. Please confirm acceptance before ordering. About Shipping: Please ensure your shipping informations are correct to avoid delivery issues. All orders are shipped within 3 days after payment. Delivery usually takes 8–12 days, The specific delivery time is depend on circumstances. If you have any questions during your purchase, feel free to contact us. We will respond you within 24 hours.