The DJI Mavic Air records 4K30 video at 100MBPS.  This is a great feature but please be advised that a microSD card capable of 100MBPS is required.  This is the microSD card that I use for my Mavic Air to record 4K30 video.

Available on Amazon.comSamsung 64GB 100MB/s (U3) MicroSDXC EVO Select Memory Card with Adapter (MB-ME64GA/AM)