2pcs Portable Pen Type 0-9990PPM Digital Water Quality TDS pH Tester with Backlight Measurement Detection Water Purity Monitor for Aquarium Pool Feature: 1. The pH pen of this set of products adopts one-key automatic calibration and manual calibration of the calibration solution, which solves the problem of long storage time for automatic calibration and cannot be accurately calibrated; 2. The top of the pH pen adopts a good sealing process to prevent self-consumption in a humid environment; 3. The TDS pen screen has dual backlights, the screen with a TDS value of 40 and below displays green, and the screen with a TDS value of 40 and above displays red. Specification: Material: ABS plastic shell TDS detector size: 155*25*14mm Power supply: 2*LR44 button battery Test item: TDS value Measuring TDS range: 0-9990PPM Resolution: 1PPM Error: ±2% PH detector size: 155*30*15mm Power supply: 2*LR44 button battery Operating temperature: 0-80℃ Test item: PH value Measuring range: 0.0-14pH Resolution: 0.01pH Error: ±0.05% Applicable industries: Households, hospitals, swimming pools, disease control centers, water plant laboratories, aquaculture Product description: TDS refers to the total dissolved solids in water, which can be measured by an instrument or test paper. Generally speaking, 0-50 is "ideal drinking water" and 50-100 is "mineral water". The higher the TDS reading of tap water, the more likely the water is to have problems. Note: Due to the different monitor and light effect, the actual color of the item might be slightly different from the color showed on the pictures. Thank you! Please allow 1-2cm measuring deviation due to manual measurement. Included: 1 X pH Detector 1 X TDS Detector