Internal Measurements are Questionable.
The Transporter assembled easily with no issues. When I was measuring the items I was going to transport in the Transporter, the 21-1/2" would be tight. Once I trail fit the items into the Transporter, I discovered that the 21-1/2" measurement is rim to rim and not at the floor level. The tail lamps are recessed into the body of the Transporter. The depth of the tail lamps and latch assembly takes two (2) inches away from the 21-1/2". To be able to use the Transporter, I will have to load the heavier stuff in the top half of the box. Not what I was expecting.