Sony Lightweight 4GB PX Series MP3 Digital Voice IC Recorder With Built-In Stereo Microphone, 4GB Internal Memory Expandable to 32GB with microSD Cards, USB Direct-PC And Mac Compatibility, Scene Select, A-B Repeat Perfect For Playback Convenience, Batteries Included Built-in 4 GB flash memory - Up to 1,073 Hours of maximum recording time USB Direct-PC & Mac compatibility & Memory Card Expansion Slot (microSD/SD HC/M2) Stereo Microphone for 75  15 kHz audio response With Intelligent Noise Cut for noise-free recordings Track Mark function to locate important recording segments Add/Overwrite function for fast and easy editing on the go