1. Professional Dissolved Oxygen Tester Kit: Dissolved oxygen meter in % or mg/l,supports and 0 point calibration, zero water solution(not include), which is easy to calibrate. -100 Portable DO Tester comes with auto temperature compensation. 2. Versatile Measuring Range and Wide Application: -100 Digital DO meter accurately measures dissolved oxygen (DO) in the range of 0-200.0% or 0-20mg/l, pH range 0.00-14.00,Salt range 0-2000ppm,2.0-100.0ppt, EC range 0.0-1999S cm,2.0-200.0mS cm, and temperature range 32.0-122.0/0-50C. 6 in 1 DO pH Salt ppm Conductivity Meter is the good monitor tool for Aquaculture, Aquarium, Farm, Lab, Pool,industrial water quality checks, fish tank, pond, Making wine, Environmental monitor and so on. 3. Handheld Dissolved Oxygen Meter for Aquaculture Farm: Dissolved oxygen and salinity are important factors in aquaculture. Salinity affects the content of dissolved oxygen in water. The digital salt testers remind you the health status of your fish in real time. It is your most powerful assistant for fish lovers and aquaculture farmers. 4. Smart Portable 6 in 1 DO pH SALT Tester: Digital pH Meter can test DO pH EC Salt Temp Simultaneously. With different color connector on the meter,only screw on the probe with same color, then get the measuring reading accurate and fast. Accurate replaceable DO probe with anti-collision cap.Even amateurs in dissolved oxygen measuring will be up and running reliably in no time. Please note: the physical slightly color difference or difference, does not affect the use, please do not mind, thank you Colour:Photo Color Material:ABS Package Contents: 1 x Multifunction DO meter 3 x Probe 1 x English Instructions Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.