I guess I OUGHT'A tell you what is in it.!
it's a Schwinn Luggage carrier (K-Mart) with he adjustable platform removed.
I Extended it with a piece of 12" s 1/2" square slotted steel adjustable wall shelf bracket screwed into the luggage carrieri mount.
I used the steel strip that is woven though the end of a length of link-wire fencing to attach to the post by bending and drilling for the wheel struts.
The Schwinn carrier mounts to the seat post had to be adapted with a piece of split thin-wall PVC pipe (irrigation pipe) to shim up the diameter differences.
Yodar