My GT came with one.. It's not a great thing. The design and workmanship is less than 7th grade shop class. It's horribly heavy and puts immense stress on the trailer's step. I weigh 175 pounds and really didn't like the way it felt loaded. It'd be OK if you supported it with a block of wood.
It folds flat for convenience of storage, but there's no place to store it where it doesn't scratch and scrape and mar whatever it comes in contact with. I jettisoned the POS because for what it weighs, I'd rather carry my spotting scope, cameras, field binoculars and a sewing machine.
It only works comfortably if the trailer's level creates a normal rise, otherwise its two or three or five inch rise from the ground is uncomfortable and a real shin gouger.
It's a big heavy thing that has an infrequent single purpose. You must deploy your step, then insert the contraption if required. A foam “yoga-step” block is way lighter and can multi-function as seating or footstool or flotation device… and more comfortably stored.
An image is on eBay's completed listings under Airstream second step