The 225-520-A Pocket Sling Psychrometer is only 7.5" in overall length and comes with a convenient pocket-size carrying case. The two 5.5" red liquid filled thermometers are attached to an aluminum back with a handle for whirling. The handle folds down when not in use. Instrument range is either +20° to +110°F or -5° to +45°C. Humidity tables are provided. Replacement wicks are available.