Specification: Item Type: TDS Test Pen Model: TDS 3 Material: ABS Battery: 1.5V button cell LR44 x 2 (without battery) Uses: Domestic water, swimming pools, aquaculture, environmental water quality, agricultural water, fish tank water quality, greenhouse flowers, barrels of water, community water stations Basic Parameters: Test Range: 0-9990ppm How to Use: 1. Open the pen cover 2. Press ON or OFF to power on 3. Put the pen into the water to be tested, gently shake, wait for the value to stabilize press the HOLD button to lock the value 4. Take the test pen out of the water, watch the value shown on the display Package List: 1 x TDS Test PenScope of Use: Water quality test pen is suitable for domestic water, swimming pool, aquaculture, environmental water quality, agricultural water, fish tank water quality, greenhouse flowers, barrel water, community water station. Ti Alloy Probe: This water quality test pen has a sensitive probe of corrosion resistant Ti alloy, which is sturdy and durable and works stably. Backlit HD Display: The water quality tester has a backlit HD display, which can be measured at power on and operated by the button. Accurate Testing: This TDS test pen can achieve accurate and fast testing values, giving you a good data reference effect. Easy to Use: Get your testing results in seconds. Turn on, immerse the electrode in the testing liquid, press Hold button and read the numbers?.