Portable Mini Voice Amplifier For Teaching Guiding Speaker Presentations Up To 15 Hours 20W With Microphone (Black) Long durable time up to 15 hours when battery charge completed (generally 2-4 hours) Long life internal rechargeable batteries Loud sound, maximum output power: RMS 20W With Belt Clip and Great clarity, great value for money For tour guides, teachers, lecturers, entertainers, cheerleaders, sales promoters, etc, protect your precious voice box and use portable voice amplifiers.