Abstract: There is provided a device for mitigating physical shock to an object to which it is attached. The device includes a body having a through-bore extending from one end to another. A sliding mass is positioned within the bore hole such that it can slide within the through-bore. A first end cap is slidingly disposed in said body hollow volume at one end of the body, and a second end cap is slidingly disposed at the other. End cap and body combination is filled with a liquid. Responsive to an impact along the body axis, one of the end caps is partially displaced into the body and at least a portion of the liquid changes phase from a liquid phase to a vapor phase.