The Sony ICD-PX440 Digital Flash Voice Recorder has 4GB of internal flash memory and can record up to 44 hours of mono audio in 192 kbps MP3 quality. Additional storage can be provided via its microSD memory slot and optional memory cards. The ICD-PX440 has an Intelligent Noise Cut which is designed to automatically reduce ambient noise during recording. The A-B Repeat function allows you to set a beginning and end of a passage for looped playback. It is powered by the 2 included AAA batteries.