Pereskiopsis spathulata, (6" cuttings)
Perskiopsis spathulata is one of the few cactuses that has leaves. It's also the most commonly used grafting stock for small cactus seedlings.
These cuttings are all around 6" and are grown in the shade to make sure that they have tips soft enough for grafting.
Anyone who has grown these before knows that they root extremely readily in either wet or dry soil. They are unstoppable growers! :)