Up to 6.5 litres. You fill it yourself from a tap, and how much you put in is the only setting on the board. A part-filled tank moves less mass under the footpad than a full one, so the fill level is worth experimenting with before it settles at whatever you prefer.

The board is 7.5 kg (17 lb) empty, and a full 6.5 litres adds about 6.5 kg, so a filled board is around 14 kg. It still moves room to room in one trip. The shipping carton is a separate figure at 9 kg.

250 kg, which is 551 lb. It is the highest user rating on any of the smaller NOHrD pieces, higher than the 200 kg on the HedgeHock and the VivaBall and the 150 kg on the Sling.

64 cm across and 18 cm tall. The 64 cm diameter is wide enough for two feet at shoulder width, for kneeling, and for two hands in a push-up position. At 18 cm tall the step onto it is short, and it stores on its edge against a wall or under a bench.

Squats, lunges, sit-ups and push-ups are the four the board is sized around, along with plain standing balance training. The idea is the same in every position: the surface is moving, so whatever you are doing is done on a base that will not hold still.

A dome or a roller is a fixed pivot, so the tilt it gives is repeatable. Water has no pivot: it runs to the lowest edge, arrives a moment after the board has moved, and starts moving again as soon as anything changes. The surface under your feet therefore keeps changing while you are on it. The fill level sets how much water is doing that.

No. It arrives built in one package of 66.5 x 66.5 x 19.5 cm weighing 9 kg, and the only thing to do is fill the base. There are no tools, fixings or adjustments anywhere on it.

Real wood veneer in six finishes, Shadow, Oak, Vintage, Club, Cherry and Walnut, cheapest to dearest in that order, and those six are the ones we stock. The pad is veneer rather than solid timber, so compare it on that basis with the solid-wood pieces in the range.

On its edge against a wall, under a bench or flat on the floor as a low table. At 64 cm across and 7.5 kg empty it is light enough to stand away on your own, and the base can be emptied of its 6.5 litres first if it is being carried any distance or stored somewhere cold.

The 250 kg rating and the sealed base are what make it practical in a shared room: nothing to adjust between users, nothing to break, and a rating high enough that nobody needs to check it. The NOHrD warranty covers private and commercial use alike.

One year from the date of first shipment, extended to two years on components and two years on wooden components if you register the board within the first year of purchase. Spare parts carry ninety days.