OLYMPUS VoiceTrek IC MicroSD Blue Recorder, 4GB, Compatible, V-842,

Recording file format: MP3, Playback file format: MP3, Frequency response (L): 40Hz, Frequency response (H): 17000Hz, Sampling rate: 44.1kHz/128kbps Memory capacity: 4GB, Supported memory cards: microSDHC Number of built-in microphones: 2, Microphone movement: Not supported, Directional switching: Not supported, External microphone: Supported Low-cut filter: Supported, Noise cancellation: Supported, Automatic recording: Supported USB direct connection: Supported, Type: 2 x AAA, Battery life (recording): 110 hours, Battery life (playback): 90 hours