Measure ORP simply and accurately with Thermo Scientific™ Orion™ ORP Standards for Redox/ORP Electrodes. Orion OPR standards are stable for up to a year (unopened) and can be used directly from the bottle with no mixing or diluting. Orion OPR standards are designed for use with gel-filled ORP/ATC Triode™ electrodes (9179BNMD and 9179BN); refillable ORP/ATC Triode electrodes (9180BNMD and 9180BN); glass-bodied ORP electrodes, (9778BNWP and 9778SC); and Sure-Flow™ ORP electrodes, (9678BNWP and 967800).