Fieldpiece Instruments’ ARH4 measures relative humidity and ambient air temperature directly, and calculates wet bulb or dew point. The accessory head easily snaps onto any Fieldpiece stick meter, and can be used as a stand-alone meter when connected with the Fieldpiece EHDL1 Electronic Accessory Handle. It measures ambient air temperature ranging from 32F to 140F, with a conversion rate of 1F/1mVDC, accuracy of + 1F, resolution of 0.1F and a 10-second time constant. Relative humidity ranging from 0% to 100%, can be measured, with a conversion rate of 1% RH/1mVDC, accuracy of + 2.5% and a 60-second time constant. www.fieldpiece.com, 714/257-9060.