Abstract: A shock absorber apparatus for inclusion in a tool string which consists of outer and inner casings telescopically assembled with one casing having an uphole threaded joint member and the other casing having a downhole threaded joint member. The concentric casings then define spaced, sealed voids communicating through a metering sleeve clearance that are filled with a compressible oil. Shock wave induced relative movement of the casings from either direction causes a shock absorbing instantaneous displacement of oil from one void to the other via the metering clearance. Alternatively, coil springs may be disposed in the voids to aid in shock absorption.