The Vaisala HM40 series hand-held meter is a compact and portable humidity meter that provides reliable measurements in a wide range of applications. It is the ideal spot-checking tool for everything from structural moisture measurement and air conditioning systems to humidity measurement in industrial production processes and life science applications. There are four different models available: HM41, HM42, HM45, and HM46. HM40 incorporates Vaisala HUMICAP sensor that provides high accuracy, excellent long term stability, negligible hysteresis, and insensitivity to dust and most chemicals. The meter also features a hold button that retains the measurement data until it has been recorded, and automatic shut off. The HM40 has a large, user-friendly graphical display and easy-to-use push buttons. The user interface is simple and intuitive, and available in 10 languages. Also, many settings can be modified to meet users’ individual needs. In addition to relative humidity and temperature, the HM40 provides five calculated humidity parameters, all of which are available in metric and non-metric units. The HM40 is powered by 2 AA batteries or rechargeable AA sized NiMH batteries. Each model also comes with a handy belt clip and case. Whats Included: batteries, probe, and NIST-traceable calibration report supplied by vendor. Lightweight, pocket-sized meter with superior accuracy Larger graphic display that shows when the measurement is stabilized Provides 6 calculated measurements: RH, Temperature, Td, Tw, a x, h Multilingual user interface with 10 language options Easy-to-use menu Replaceable probe.