Blue grid fin can perform two rotations around horizontal and vertical axes.
Yellow and violet actuators are grounded.
Green arms and yellow actuator are coaxial.
It is used on rockets or bombs for flight control.
At high Mach numbers, grid fins work better than planar fins.
I could’t find any document on the transmission for grid fins so the mechanism in this video is my imagination only.
The video was made upon a YouTuber’s request.