Features: 1AUTO IDENTIFICATION: The test pen has automatic identification function, long press CAL after power on to calibrate with one key, use the square all over. 2HIGH ACCURACY: This pH test pen has a tisensitive probe that gives results in a second, which is fast and accurate. 3POCKET SIZE: This test pen is miniature in stature and can be carried around to test the purity of water anytime and anywhere. 4ABS HOUSING: The PH test pen is made of ABS as the housing, which is lightweight but hard and wear resistant, and has a long service life. 5WIDE APPLICATION: PH test pen is suitable for testing domestic water, swimming pool, aquaculture, agricultural water, fish tank water quality, greenhouse flowers, and barrel water. Package included: 1 x PH Test Pen 2 x PH Reagent 1 x Screwdriver 1 x Plastic Box