Review on REED Instruments R8080 Datalogger Bargraph by Vedavyas Fleming

That's three stars because it came with no paper certificate, just a sticker on the unit, and the description said "This product includes a calibration certificate traceable to NIST (National Institute of Standards and Technology)" as well as the calibration period from April 19, 2016 to April 19, 2017, so I just lost five months of the certificate without using it.