Apparatus for reducing sensitivity of an article to mechanical shock comprises a frame; first and second planar masses mounted in the frame for bi-directional movement relative to the frame along a first axis of displacement; a first lever pivotable about a first fulcrum secured to the frame; the lever having one end connected to the first mass and the other end connected to the second mass, and the fulcrum being disposed between the ends of the lever; whereby the torque exerted about the fulcrum by the first mass is countered by the torque exerted about the fulcrum by the second mass in response to a mechanical shock applied to the frame along the axis of displacement such that an article carried by the first mass in use has reduced sensitivity to the shock.