Just that the rear fold under is like a Kickstand .
as long as the seat post goes down as far as the stop disc on the forward end of the rear brake Bolt,
the rear wheel will not unfold, when you lift the folded up bike.


this is their version of the Carry Freedom 'Y' trailer.

with a Platform, Or adding a box like the Rubbermade shown above, 3rd post.
https://www.biketrailershop.com/wand...ll-p-1580.html

I see their lowest price Kid Trailer is for the moment reduced, on that site https://www.bikekidshop.com/thule-ch...e2-p-3491.html