A flexible hydraulic muscle (20) comprising a fluid port (22), bellow (24), end seal (28) and attachment ring (30). Bellow (24) also defines a retracting spring bias for generating contracting forces within muscle (20). Fluid port (22) is designed to provide an anchor point for the muscle, while at the same time, providing a means to introduce and remove hydraulic fluid from bellow (24). End seal (28) and attachment ring (30) provide the second connecting point for the muscle. These two anchor points on each end of bellow (24) provide connection points to communicate contracting force from bellow (24) into useful work. End seal (28) is securely attached or bonded to the end of bellow (24) to provide a fluid tight seal, and designed to resist longitudinal forces on the connection.