Abstract: A structural support comprises inner and outer elements which are telescopingly engaged, a cage secured to the inner element and having apertures in which balls are disposed which are disposed radially between the two elements, and a frangible connection securing the two elements against relative axial movement. In the locked relative positions of the elements, the outer element has locally an increased internal diameter portion and the balls are radially disposed in this position or are moved into the portion on being subjected to an axial force which breaks the frangible connection, so that the relative axial movement of the elements results in the ball plastically deforming the outer element and absorbing energy from the force to protect the body carried by the support. The support can be used to provide a brace operating as a strut and/or a tie, or a shock absorber, or, by mounting a damping piston slidably in the inner tubular element can provide a shock absorbing piston and cylinder unit.