The RetraStrap attaches to the handle of most wheeled carry-on bags with the usual size handles 1/2 inch to 1 inch in diameter.
It works on bags with the T handle but it depend on the shape of the handle.
It does work on spinner bags, (the ones with 4 wheels) however you can only pull the bag in the tipped position.
The RetraStrap is designed to work best with normal size carry-on bags, the typical ones that you take on the plane weighing between 15-25lbs.  It is not recommended for the large check-in bags weighing close to 50lbs.