The service life of the built-in battery is about 5 months depending on the frequency of use. The battery can be replaced with a one when it is exhausted. Battery model: LR03 alkaline zinc manganese batteryPH/EC/TDS/ORP/TEMP/residual chlorine six-in-one Bluetooth water quality penNote:Make that the sealing ring (its own) is tightened and put into the water. No sealing ring or untightening will lead to water ingress.Type:B:With calibration powderColour:As ShownMaterial:ABSSize:160x26x90mmPackage Contents:1 * Water quality detector5 * calibration powderOnly 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.