Signedplate on top panel: RADIO WAVEMETER AND KOLSTER DECREMETER / MADE FOR NAVY DEPT. (BU. S.E.) BY / NATIONAL ELECTRICAL SUPPLY CO. / WASHINGTON, D.C. / REQ. 1702 N.S.A. CONT. 36904 5 - 23 - 18 / TYPE CN 1215 SERIAL NO. 123 / (greek leter lambda) 100 - 3500 METERS
on face of meter: CURRENT SQUARED METER / CAR 330 SERIAL NO. 66956 AR / MADE BY / ROLLER-SMITH CO. / BETHLEHEM, PA. / FOR USE IN HORIZONTAL POSITION