Oakton pH buffer solutions have pH/temperature tables printed on the labels for accurate calibrations (not on 60 mL, but included as insert). Manufactured under ISO 9000 quality guidelines and traceable to NIST standards. If not opened, the shelf life is 2 years; once opened, use pH 4 and pH 7 within 90 days, pH 10 days. 30 day options. 1.68 inches. buffer available in transparent pH 4.01 buffer available in red, pH 6.86 buffer available in transparent pH 7.00 buffer available in yellow - pH 9.18 buffer available in transparent buffer - pH 10.01 buffer available in blue - pH 12.46 buffer available in clear. Standardized against NIST traceable pH reference references for meters with meters to 0.01 inches. resolution. Sold in individual 33.8 fl oz (1 liter) bottle. Ideal for laboratory and field analysis. All Oakton pH buffers are traceable to NIST standard reference materials. The buffer solution allows you to calibrate pH instruments to ensure accuracy. If unopened, shelf life is 2 years NIST/USA buffer value of pH 4.01