Digital Recorder: 51.5*37*15mm, recording distance 5-10 meters, number of two microphones, recording formats MP3, WMA, WAV.HD Recorder: Intelligent loop recording, intelligent time stamp, automatic saving after power failure, using photosensitive lens, 1080P six lenses, no light and no sound when recording, lens: F/NUMBER 2.25.USB RECORDER: Supports recording while charging, can be a U disk recorder, independent one-key recording, one-key video and audio synchronization.4. Easy to use, powerful little voice recorder. A pocket-sized recorder that can be used to secretly record conversations and meetings. Capture and save important conversations and meetings. The sound is clear and the device discreet.5. Recording conversations without being seen has never been easier. This mini recorder captures sound from a distance, which you can listen to later on your computer.