Made of beautiful aluminum structure, this speaker measures 2" x 2" x 2" which is compatible with the TF card and most phones or MP3. Your brand can be printed or laser engraved on the aluminum shell. Build in 150 mAh battery and USB interface, single track RMS 3W THD 10%, frequency response 150-18000Hz(3dB), signal noise ratio exceeds 80dB. It's an ideal promotional product for any occasions and events.