Features: 1. Turn any hollow core into a speaker: These bone conduction speakers are compact and versatile, allowing you to enjoy a unique sound experience in various environments. Use them with different hollow objects to create o output. 2. Different sounds with different surfaces: Utilizing bone conduction technology, this speaker delivers a customizable o experience. Experiment with various surfaces such as glasses, guitars, paper boxes, plastic containers, photo frames, headphones, or dashboards to achieve diverse sound effects. 3. Portability: Lightweight and compact design makes it easy to carry and use anywhere. 4. Small but powerful: When paired with suitable materials like thin plastic containers or buckets, the speaker can produce strong sound output up to 115 decibels, with customizable sound quality. 5. Multifunctional use: Supports music playback, podcasts, hands-free phone calls, conference calls, and gaming o. Includes built-in FM radio functionality for listening to radio stations and o content. Specifications: Capacity: 400mAh Function: Bone Conduction Speaker, FM Radio Wireless Version: 5.0, A2DP, HFP Supports Wireless Stereo Built-in FM Radio Bone Conduction Transducer: 3Watt Frequency Range: 120Hz - 16kHz Built-in High-Sensitivity Microphone Battery: 400mAh Polymer Battery Charging Port: USB-C (not compatible with fast charging) Recommended to use FM function outdoors; connect USB cable during use. Material: Metal Color: Black Package Contents: 1 x Bone Conduction Speaker 1 x Charging Cable Note: Light reflection and display differences may cause slight color variation between the image and the actual item. Measurement tolerance: +/- 1-3cm.