Fits wheelchairs with frame sizes ranging from 14.96 inches to 20.47 inches and tubes with sizes of 22mm and 25mm. Compatible with wheelchair tubes of outside diameters 8.66 inches and 9.84 inches. Adjustable headrest for customizable positioning. Easy to install and remove without the need for tools. Service: We place great emphasis on our customers' shopping experience. If you have any questions, please feel free to contact us; we will respond to you within 24 hours!