The ZETA® 7021 is a self-contained ,electro-optic instrument designed to measure and display the UV irradiance emitted by a UV spot curing system. The units displayed are watts per square centimeter. Decreased radiant power related to the degradation of UV lamps, light guides and reflectors, can result in declines in process efficiency or incomplete curing of UV light curing products. The Zeta 7021 is designed to provide the operator with instant feedback as to the performance of the spot curing system. It accepts both 3 mm and 5 mm diameter wands. The Zeta 7021 Spot Radiometer is traceable to the National Institute of Standards and Technology (NIST). The unique detachable sensor head requires recalibration only once per year (vs. every 6 months for the competitive models). Requires a 9 volt alkaline battery (not included).