3"x 4" slides of standards and units and cassette tape of WWV.

Standards and Units. TIME: A Cassette Tape Recording of the WWV Broadcast is available. Also: Live Time Signals from WWV-if you are in a room that has radio reception. 2.5,10,15,20, and 25 Meg. ( at 5 minute intervals). Also a 440 and 600 hz tone. LENGTH: Slide of National Bureau of Standards Standard Meter Bar. MASS: Slide of National Bureau of Standards Standard Kilogram