HOTECH 391 Blackbody Calibrator, a great performance calibration system, is design for calibrating infrared pyrometers. This series is special designed with wide open aperture and deep cavity which provides the excellent result of emissivity. Model 391 is available functioned within the broad temperature range of 100 to 700°C. Moreover, wide open aperture design has ability to provide a steady, repeatable calibration point which allows the user ease to calibrate most infrared pyrometers quickly and accurately. The deep prolong cavity offer high emissivity enabling the user to calibrate virtually with any infrared pyrometer with a 60 mm diameter aperture. This model has the option to choose the additional compunction module which able to communicate with applying RS-232, 422, or 485 computer interface.