Great for water, laboratory or plant use, the Oakton WD-35425-05 PT Testr 35 features single-junction pH electrodes for longer life and wider range of sample compatibility. Pin-style conductivity sensors feature stainless steel electrodes for chemical resistance and durability. Replaceable sensor module saves you money by reusing the meter body. Advanced features of the WD3542505 include auto-shutoff, user-adjustable temperature coefficient, self-adjusting TDS and salinity factor, and low-battery indicator.