Abstract: The invention relates to a device (1, 3, 37) for exerting an external pressure on a human body part. The device, which is designed to surround the body part with comfortable fit, comprises components (15, 19 and 28) of memory material, such as memory metal. By heating the components, e.g. by conducting electric current through them, they will assume a different shape, e.g. a shorter length, the device being adapted to be contracted so as to "squeeze" the body part. When the components are thereafter cooled, they will resume their previous shape and the contraction ceases. The device is intended, inter alia, to prevent pooling of blood in body parts of a pilot when subjected to G-forces, and to increase, by recurring contractions, the blood circulation in the body parts surrounded by the device.