donated equipment they have received. Organizations that accept donations in the form of money for wheelchairs typically have the wheelchairs manufactured and distributed in large numbers, often in developing countries. Organizations focusing on wheelchairs include Direct Relief, the Free Wheelchair Mission, Hope Haven, Personal Energy Transportation, the Wheelchair Foundation and WheelPower. In the United Kingdom wheelchairs are supplied and maintained free of charge for disabled people whose need for such a chair is permanent. Seating systems Wheelchair seating systems are designed both to support the user in the sitting position and to redistribute pressure from areas of the body that are at risk of pressure ulcers. For someone in the sitting position, the parts of the body that are the most at risk for tissue breakdown include the ischial tuberosities, coccyx, sacrum and greater trochanters. Wheelchair cushions are the prime method of delivering this protection and are nearly universally used. Wheelchair cushions are also used to provide stability, comfort, aid posture and absorb shock. Wheelchair cushions range from simple blocks of foam costing a few pounds or dollars, to specifically engineered multilayer designs with costs running into the hundreds of pounds/dollars/euros. Prior to 1970, little was known about the effectiveness of wheelchair cushions and there was not a clinical method of evaluating wheelchair seat cushions. Most recently, pressure imaging (or pressure mapping) is used to help determine each individual's pressure distribution to properly determine and fit a seating system. While almost all wheelchair users will use a wheelchair cushion, some users need more extensive postural support. This can be provided by adaptions to the back of the wheelchair, which can provide increased rigidity, head/neck rests and lateral support and in some cases by adaptions to the seat such as pommels and knee-blocks. Harnesses may also be required. Accessories There is a wide range of accessories for wheelchairs. There are cushions, cup holders, seatbelts, storage bags, lights, and more. A wheelchair user uses seatbelts for security or posture. Some wheelchair users want to use a seatbelt to make sure they never fall out of the wheelchair. Other wheelchair users use a seatbelt because they can't sit up straight on their own. See also Mobility scooter Motorized wheelchair Wheelchair ramp Wheelchair DanceSport Wheelmap.org, web mapping project (collects information worldwide about wheelchair accessibility of places) Lift chair Standing wheelchair Notable wheelchair manufacturers Everest and Jennings Küschall Otto Bock Invacare TiLite Mogo Wheelchairs References