Features: 1. Turn any hollow core into a speaker: These bone conduction speakers are compact and versatile, enabling a unique o experience in various environments. Transform any hollow surface into a speaker anytime, anywhere. 2. Different sounds with different surfaces: Utilizing bone conduction technology, this speaker offers a customizable o experience. Enjoy varied sound outputs by attaching it to different surfaces such as glasses, guitars, paper boxes, plastic containers, photo frames, headphones, or dashboards. 3. Portability: Lightweight and compact design makes it easy to carry and use on the go. 4. Small but powerful speakers: When attached to suitable objects, the speaker delivers strong o output up to 115 decibels, allowing for personalized sound quality. Recommended for use with thin materials like plastic boxes or buckets. 5. Multifunctional speakers: Use for listening to music, podcasts, making hands-free phone calls or conference calls, gaming, and enjoying immersive sound effects. The built-in FM radio function allows you to tune into radio stations and o content. Specifications: Capacity: 400mAh Functions: Bone Conduction Speaker, FM Radio Wireless Version: 5.0, A2DP, HFP Wireless Stereo Supported 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 and 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 variations between the product color in images and the actual item. Measurement tolerance allowed is +/- 1-3cm.