PH-80: An economically priced, reliable pH meter that is ideal for testing applications such as hydroponics & gardening, pools & spas, aquariums & reef tanks, water ionizers, drinking water and more. FEATURES Measures pH and temperature One-touch automatic digital calibration Water resistant Simultaneous temperature display Sleek, lightweight design Large LCD display Automatic Temperature Compensation (ATC) Auto-off function, data-hold function and low-battery indicator Includes storage solution in a sponge embedded in a translucent cap Factory Calibrated: The PH-80 meter is factory calibration to pH 7.0. The meter can easily and quickly be recalibrated with digital calibration to pH 4.0, 7.0 or 10.0 using the meter's simple one-touch process Includes a cap, batteries, storage solution and pH 7.0 buffer PH-200: FEATURES Measures pH and temperature Auto-ranging three point calibration with digital fine tuning Includes 4 pH buffer solution in a sponge embedded in a clear cap, so you can see if it's dried up Waterproof housing Simultaneous temperature display Measurement Range: 0-14 pH Digital Calibration (push button)Auto-off function, data-hold function and low-battery indicatorDisplay: large and easy-to-read LCD screen includes simultaneous temperature readingFactory Calibrated: The PH-200 meter is three-point factory calibrated to 4, 7, and 10 pH. The meter can be recalibrated with digital calibration using the push buttons, rather than a screwdriver. Includes a cap, batteries, and lanyard SPECIFICATIONS pH Range: 0-14 Temperature Range: 0-80°C/32-176°F Resolution: 0.01 pH; Temperature resolution is 0.1°C/F Accuracy: +/- 0.02 pH Calibration: Digital calibration by push button Electrode: Replaceable glass sensor and reference tube electrodes Housing: Waterproof (submersible; floats) Power source: 2 AA batteries (included) Dimensions: 18.5 x 3.4 x 3.4 cm (7.3 x 1.3 x 1.3 inches) Weight without case: 96.4 g (3.4 oz)