This trailer had a 2 ton capacity mounted on dual walking beam axles with a unitized body and was the basis for many derivative units. All of those are mentioned at left. 

An M-22 Directors Trailer

The CCKW was the prime mover for this type of trailer. All G-221 trailers were equipped with CCKW compatible tires and electric brakes. Some trailers models were equipped with an adjustable landing wheel mounted in front of the body while others were equipped with 2 or 4 leveling jacks mounted on the corners of the box. The attaching lunette was fully height adjustable. Some models were also equipped with Hand operated parking brakes.