T831 Micro Cassette Cellular Phone Recorder T831 Micro Cassette Cellular Phone Recorder Mobile and phone recording; Built in microphone for memo tape recording 2 tape speeds 1. 2 cm/sec, 2. 4 cm/sec; Speaker volume control; Pause function Fully portable; Uses 2 AA battery (batteries not included) 3V DC power (AC adapter not included); Voice activated