1.Precise Water Quality MeasurementThe TDS test pen provides highprecision measurement of total soluble solids content in water (09999ppm), ideal for checking water quality in various applications such as drinking water, aquariums and agriculture. 2.Wide ApplicationsPerfect for coral and fish farming, fertilizer adjustment and filter testing this tester helps you monitor water quality in real time and take timely action to keep your plants and fish y. 3.Userfriendly design: With a waterproof IPX6 housing and a highquality titanium alloy probe, the TDS test pen is both durable and easy to use. The digital LED screen shows the results clearly and understandably, giving you instant feedback on water quality. 4.Energy efficient and portable: Equipped with an energyefficient microprocessor and a compact size (15 x 1.6 x 1.6 cm), this water quality test pen is easy to carry and is perfect for use at home or on the go. The two included AG13 button batteries ensure a long life.