Oakton pH buffers are compared against, and are traceable to, NIST Standard Reference Materials. Each bottle includes a NIST-traceable calibration report stating accuracy at 25C to 0.010 pH. Color-coded and colorless buffers are available in 500-mL, 1-L, or 4-L packaging sizes. Store at room temperature. Certified Reference Materials (CRM) meet federal, state, and or local agencies strictest mandates, and deliver exact calibration results for any pH meter. A2LA ISO/IEC 17025:2005 (1750.01) (Calibration Laboratory) and ISO Guide 34 (Certified Reference Material Producer) provide highest achievable levels of product production, documentation, and accuracy. Additional accreditations include ISO 31 (content) and ISO 35 (statistical analysis). ISO 9001 ensures that world-class product standards for Materials are always met. Traceable products are calibrated to NIST-traceable standards and ready to use as soon as you receive it.