Zorbing (orbing) is an extreme recreation (some consider it a sport) which includes you getting in an orb made out of transparent plastic, and then rolling downhill. It is usually performed on a gentle slope, but can also be done on a level surface, permitting more rider control. In the absence of hills some have constructed inflatable, wooden or metal ramps. The zorb is double-sectioned, with one ball inside the other with an air layer between. Orbs are lightweight and made of flexible plastic. Some orbs also have straps to hold the rider in place, while others leave the rider free to walk the orb around or be tossed about freely by the rolling motion - water can be added inside, and this is commonly called “hydro zorbing”. A typical orb is about 3 metres (10 ft) in diameter, with an inner orb size of about 2 metres (6 ft 7 in), leaving a 50–60 centimetre (20–24 in) air cushion around the riders. The plastic is approximately 0.8 millimetres (0.03 in) thick. You don’t have to go in the orb alone since there are two types of orbs, harnessed and non-harnessed. Non-harness orbs carry up to three riders, while the harness orbs are constructed for one to two riders. Zorbing is performed at commercial locations, where prospective riders pay a fee for each ride or for a whole day’s activity, the most popular being in New Zealand.