Milwaukee Smart Portable Meters deliver fast, reliable results. The pH Meter measures from 0.0 to 4.0 with ± 0.2 percent accuracy. Easy-turning dials on the front of the unit make the required two-point manual calibration a snap. The pH Meter measures from 0.0 to 14.0 with 2 percent accuracy. Meters come with a probe, 9-volt battery good for hundreds of hours and a 20-milliliter sachet of calibration solution. Each unit is backed by a two-year warranty on meter and a one-year warranty on probe.