original reinforced galvanzied steel "holdfast" incandescent lamp guard or "trouble light" fabricated by w.n. matthews & bro., inc., st. louis, mo. the manufacturer claimed that this guard was "foolproof" because it can be slammed with force against a solid brick wall without breaking the lamp. two reasons were given for its ability to stand this test. first, because the guard clamps rigidly to the socket and can be locked in that position securely by bending the set screw. this, in connection with the fact that the vertical protecting ribs bend outwardly and are rigidly joined to a corrugated central spreading ring, transfers all the shock of a sudden impact to the socket and away from the lamp. the second reason for its foolproof qualities was found in the fact that it has a cushion to take up the vibration of the lamp after the impact. the spiral spring cushion in the center of the guard was claimed to be the secret of its ability to withstand the roughest usage. these various features are covered by multiple patents. contains expected wear and tear, but remains largely intact. measures 4 1/2 x 5 inches.