These Certified Reference Materials (CRM) calibrate conductivity meters and probes for maximum accuracy. Traceable Available in single-use (100 mL) or 473 mL (16 oz.) sizes Easy to calibrate Polyethylene container Ideal for both lab and field conditions They are compatible with all makes of equipment, and can be used in lab or field. Accuracy at 25°C is ±0.25µmhos for 1, 5, and 10µmhos solutions, and 0.25% for all other solutions; or the uncertainty shown on the certificate, whichever is greater. Each container is labeled for calibrating conductivity in micromhos (microsiemens), resistivity in megohms, and dissolved solids in ppm. Available in 100 mL (3.4 oz.) single-use polyethylene bottles or 473 mL (16 oz.) bottles. Single-use standards make it easy to calibrate with no external contamination. An extra large opening of 4.4 cm (13/4") diameter and depth of 8.9 cm (31/2") allow probe calibration to take place in the standard’s polyethylene container. Ideal for lab/field conditions. All solutions include a serial numbered Traceable certificate to indicate traceability to standards provided by the National Institute of Standards and Technology (NIST). Double A2LA accreditation accredited certification provides the highest achievable level of quality assurance, documentation, and accuracy. CRMs are produced by A2LA accredited ISO Guide 34 certified reference material producer and by an A2LA accredited ISO 17025 calibration laboratory. Additional accreditations include ISO 31 (certificate content), and ISO 35 (statistical analysis), plus ISO 9001 DNV (certified quality manufacturer). Meet test requirements for Federal, State, and local agencies, CAP, CLSI, ACS, CLIA and complies with AOAC 973.40, EPA 120.1, Standard Method 2510 (APHA, AWWA, WEF), ISO 7888, DIN 38404, ASTM D1125, USGS I-1780, USP 645, OIML R56, IUPAC, and for A2LA/NVLAP accreditations/ISO 9000 certifications.