user to standing height. Sports wheelchairs A range of disabled sports have been developed for disabled athletes, including basketball, rugby, tennis, racing and dancing. The wheelchairs used for each sport have evolved to suit the specific needs of that sport and often no longer resemble their everyday cousins. They are usually non-folding (in order to increase rigidity), with a pronounced negative camber for the wheels (which provides stability and is helpful for making sharp turns), and often are made of composite, lightweight materials. Even seating positions may be radically different, with racing wheelchairs generally used in a kneeling position. Sport wheelchairs are rarely suited for everyday use, and are often a 'second' chair specifically for sports use, although some users prefer the sports options for everyday use. Some disabled people, specifically lower-limb amputees, may use a wheelchair for sports, but not for everyday activities. Powerchair football While most wheelchair sports use manual chairs, some power chair sports, such as powerchair football, exist. E-hockey is hockey played from electrical wheelchairs. Wheelchair stretchers Wheelchair stretchers are a variant of wheeled stretchers/gurneys that can accommodate a sitting patient, or be adjusted to lie flat to help in the lateral (or supine) transfer of a patient from a bed to the chair or back. Once transferred, the stretcher can be adjusted to allow the patient to assume a sitting position. All-terrain wheelchairs All-terrain wheelchairs can allow users to access terrain otherwise completely inaccessible to a wheelchair user. Two different formats have been developed. One hybridises wheelchair and mountain bike technology, generally taking the form of a frame within which the user sits and with four mountain bike wheels at the corners. In general, there are no push-rims and propulsion/braking is by pushing directly on the tyres. A more common variant is the beach wheelchair (beach-going wheelchair) which can allow better mobility on beach sand, including in the water, on uneven terrain, and even on snow. The common adaptation among the different designs is that they have extra-wide balloon wheels or tires, to increase stability and decrease ground pressure on uneven or unsteady terrain. Different models are available, both manual and battery-driven. In some countries in Europe, where accessible tourism is well established, many beaches have wheelchairs of this type available for loan/hire. Smart wheelchairs A smart wheelchair is any powerchair using a control system to augment or replace user control. Its purpose is to