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.Note: 1. Please allow 1-3 mm error due to manual measurement and 1-3g weight error make sure you don't mind before ordering. 2. 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 make sure you don't mind before ordering, thank you! About Shipping: 1.please pay attention to your delivery address such as: name, street, house number, doorbell/email without name, etc. is correct, or the order will not be delivered correctly. 2.All items will be shipped within 3 business days after the payment is received. Most times you will receive them within 8-12 days then. The specific delivery time is depend on circumstances. 3.During the shopping process, if you have any questions, please feel free to consult us, we will reply you within 24 hours Hope you have a pleasant shopping experience!