This is a servo control mount for the manual rectangular ducts in my house (similar to the ones shown in the pics). They accept a normal servo like the one found here

https://www.amazon.com/gp/product/B076CNKQX4

You'll need 4 M3x10mm screws to connect the top and bottom sections together along with the servo mounting screws. It's designed to work with 1/8" pop rivets (3/8" long worked for me) to directly rivet into the sheet metal of the air vents.

Note: The servo mounts to the top side of the servo box (as pictured in the CAD images) and is a pain in the @$$ to get screwed to the mount but with long handled screwdriver it's not terrible.