Extech 407026-NIST - NIST Calibration Certificate - Light Meter Heavy Duty with PC?áInterface features:?áEnhance accuracy by selecting one of four lighting types plus PC interface;?á% displays differential from reference point;?á "ZERO" Re-Calibration;?áEnhance accuracy by selecting lighting type Tungsten/Daylight, Fluorescent, Sodium, Mercury);?á Data Hold, Min/Max/Avg readings;?á Built-in RS-232 PC serial interface.