Boomphones Phantom Matte Black (Discontinued by Manufacturer) Boomphones are revolutionizing the way people listen to music. They can instantly transform into a boombox, letting you get the party started, anytime, anywhere! Power on and push the bomb to play externally. LED lights are used to indicate which mode is in action. The white LED indicates your Boomphones are internally amplified, and ready to ROCK. The red LED indicates your Boomphones are in Boombox Mode, and ready to BLAST. Turn your Boomphones into a portable amp. Plug into your computer, electric guitar, keyboard, beat machine, etc. Answer and make calls directly from your Boomphones. The inline mic allows you to take calls privately. You can push the bomb for speakerphone. Boomphones use a lithium battery that is easily rechargeable through mini USB. There are 10 hours of internal use and 5 hours of external use. The weight of Lithium ion Battery: approximately 28g Battery voltage: 3.7V Number of Lithium Battery Cells: 4600PCS(the last order) The battery is Lithium Ion