The order is based on the number of spherical harmonics used to reproduce the sound field. The higher the order, the more spherical harmonics and better the spatial resolution of the sound field. Spatial Mic is capable of 2nd Order ambisonics and uses eight capsules to capture the sound field as opposed to four capsules used on 1st order ambisonic microphones.

Learn more about ambisonics and how it is used in the Voyage Audio Journal article Ambisonics Demystified.