The energy-absorbing device comprises telescoped inner and outer members between which hard balls are confined. Its inner member is a tube with a circumferentially undulating wall that defines circumferentially alternating inwardly and outwardly opening bays and is therefore radially elastically deformable. Balls are received at longitudinally spaced intervals in the radially outwardly opening bays. The outer member has a spherical inwardly opening socket for each ball to hold the ball against displacement relative to the outer member. When either member moves lengthwise relative to the other, the balls locally elastically deform the inner member, thus dissipating energy.