It's essentially a small hard plastic toilet seat, with bumps in all the right places, and two side legs like flaps that fold out and lock into place, making it incredibly sturdy. I did worry that, in sleepy mode after not a lot of sleep, my LO might wobble off, or tip it over but, no, it proved to very very stable. The legs lock into place and you need to push the buttons in to fold back down. It comes in it's own bag and with a set of three potty liners. These, again, are much more robust than the standard ones available and are cleverly designed with detachable tags which tuck into the holders under the seat.
Simply put the liner into the 'hole' and fold the edges over the seat, tucking the ends through the grippy holes. When you remove the bag, the handles tie at the top and the bits you've tucked in to secure the liner, tear off easily so there's no spill. And you can definitely fit it more than one wee!
To use as a smaller toilet seat, push the buttons in while pulling the flap legs out again to the edges and place over the regular seat. Again, this is sturdy and doesn't slip as much as you might think, but ours will be kept firmly in the camping bags, ready for our next trip! As it folds fairly flat, it will even pack in the top of a flight case or small suitcase too if you're looking for something to take away on holiday to a hotel or apartment.