Initial Calibration of a brand new Tinytag CO2 Logger. Calibration at 500, 1,000 and 1,500ppm for 2,000ppm units and 500, 2,500 and 4,000ppm for 5,000ppm units. If you don’t order an Initial Calibration, the Tinytag CO2 Logger is still guaranteed to meet the accuracy figures on the product datasheets at the point of purchase.