Measures pH from –2 to 16 with 0.01 pH resolution; temperature range is –5.0 to 105°C with 0.1°C resolution. Features, dual-level LCD with icons for stability, automatic 1- or 2-point calibration with 2 sets of memorized buffers at 4.01, 7.01, 10.01; or 6.86 and 9.18. Celsius or Fahrenheit temperature range and automatic temperature compensation. Both models include 12VDC adapter for 110VAC power, but can be battery operated for classroom or field studies. Two-year warranty.

Model 5561B is equipped with an internal magnetic stirrer activated from the instrument's keypad.