The slosh tube is an 8-9 foot piece of PVC pipe half-filled with water and capped at each end. It weighs about 30-31 pounds. This particular tube is 3″ diameter to grip easier. Four inch can also be used. It is important that it is only filled half way as the water must be able to shift to the lower end, which creates the imbalance. It has been compared to wrestling a python.
For those that like challenging cross training, may I suggest these two exercises using one of my favorite pieces of equipment: