Binaural microphones and other devices

Sennheiser AMBEO Smart Headset

Pros:

Very easy to use.

No batteries required (powered by lightning connector).

Records with 24-bits (48,000 Hz sampling rate).

Can use as earphones.

Optional active noise cancelling or situational awareness 

Cons:

In one of two purchased units, the left microphone was 2 dB more sensitive than the right (the second is much better).

The very first unit I purchase and quickly returned had a huge phase shift at low frequencies (< ~200 Hz).

Unclear what sort of processing is happening while recording. Of course, this also makes the microphone easy to use.