Memory Foam Donut\Ring Cushion\memory foam cushion SIZE: 44cm (17 inches) Diameter and 9cm (3.5 inches) FEATURES: Moulds to contours of your body. Hypo-allergenic, anti-microbial and dust mite resistant. Unique cut-out eliminates pressure. Promotes faster healing after operations and childbirth. Highly versatile. Can be used at home, on your travels, in hospital, at work place, wheelchair etc. Sitting for long periods on a normal ring/donut cushion is not recommended as it can interfere with the blood flow causing potential pressure problems. Our ring cushion can be used for longer periods as it is made from Restore® Memory Foam, which responds to temperature and weight, shaping to the contours of your body and therefore reducing interface pressure on the affected area.