Abstract: An aspect of the invention provides an annular exercise apparatus comprising an annular body having axially spaced annular faces and inner and outer side walls, the body section having a core and a flexible cover layer and defining an aperture inward of the inner side wall and extending axially through the end faces, wherein the aperture defines an annular lip having a diameter greater than a diameter of the aperture and less than a diameter of the inner side wall.

Abstract: An improved pilot valve assembly (14) for hydraulically controlling a pressure reducing valve (12) to maintain and further vary the outlet pressure (P2) of the pressure reducing valve (12) in response to increased flow (f) through the valve (12). The pilot valve assembly (14) comprising first and second movable valve members (100,102). The first and second moveable members (100,102) being acted on by a velocity head pressure sensed by a downstream Pitot tube (90) and a downstream outlet pressure (P2) in a balanced arrangement such that they move in response to both the velocity head and downstream pressure (P2) to open and close the pilot valve (14) and so main valve (12) to both maintain and vary the outlet pressure (P2).