Calibration and test standards for turbidity measurement.

Stabilized Formazin Turbidity Standards
Formazin turbidity standards are aqueous suspensions of formazin and the reference suspension for all turbidity measurement methods. The product is stabilized by a special process and can be used for calibration, control, validation or qualification of almost all makes and models of turbidimeters.

Polymer Bead Turbidity Standards
non Ratio (EN ISO 7027) and Polystyrene Turbidity Standards Ratio (US EPA).