The memory mic is designed to be used exclusively with mobile devices, making it a brilliant for fast turn around mobile journalists, who do sometimes shoot on phones. The way it works is you connect your mobile device to the mic through the Sennheiser app, and you then have the option of just rolling sound or rolling only when you shoot video on the phone. Once you've finished filming you bring the mic back to the phone which pairs them back up and downloads the audio onto your phone, and if you've rolled video, the audio is automatically synced up with the video, meaning, fewer files to manage, and less work in post.
Now all of the audio that this mic captures is stored on the mic itself until paired back up with the phone and the audio downloaded. Meaning that there is no range to this mic, you can send it off without worrying about the signal dropping out.
The design is quite simple, there is an on/off/sync button on the side, a clip on the back and the microphone on the top. Now the mic inside the memory mic is one of Sennheisers professional mic capsules which are used in their lav mics, so you really can get professional quality audio from this mic, in a small and lightweight package (it only weighs 30 grams!)