For the dumbbell box step up, you need two pieces of equipment - a sturdy box that you can safely step upon and two dumbbells. This is a more advanced version of a regular box step up.
Begin by facing the box and holding the dumbbells in your hands at the side of your body. Place one foot on top of the box and push through that leg to bring the other leg to meet it.
Stand tall on top of the box making sure your hips are extended. Then, with the same foot you first stepped up with, step back down to the floor. The other foot will follow. This is one rep.
On the next rep, step up with the opposite foot first to ensure you're working both legs.
To make this movement more challenging, use heavier weights. You can also hold the dumbbells at your shoulders in the front rack position for an added challenge.