The In-Situ® RDO® PRO Probe uses the latest optical technology for measuring DO in demanding process environments and is EPA approved for use in Clean Water Act programs. The probe's simple design reduces user error because the calibration coefficients and expiration clock are loaded into the sensor cap. The probe operates with no drift over long-term deployments, and the calibration will last for several months if sample fouling is minimal. The probe also reduces maintenance—no hydration, conditioning, or special storage is required. The use of membranes and filling solutions are eliminated. The RDO PRO Probe's patented signal processing design responds quickly to oxygen and temperature changes and delivers consistent, reproducible results.