Conservation. Glass gauges replacing steel. Glass gauges of various types are replacing steel gauges at the Frankford Arsenal. Left, top to bottom: double-end gauge, "go" plug gauge, ring gauge. Right, top to bottom: "not go" plug gauge, double and solid-handle plug gauge, double-end taper-lock standard, handle plug gauge. Glass gauges are lighter and cheaper than steel, permit greater visibility in inspection, are not as much affected by room temperatures and heat of operators' hands, are not corroded by perspiration, need no protection against rusting, do not acquire burrs that would change the effective sizes. They can save the annual use of 250 tons of critical tool steel in government arsenals alone