Conservation. Glass gauges replacing steel. Markings are carried on a label pasted on the handle of a glass plug gauge, which replace steel gauges at the Frankford Arsenal. Markings on other gauges are produced by acid etching. 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