Apera Instruments TN400 Portable Turbidity Meter, Large Colored TFT display with graphic and text guides, Accuracy: ±1% or 0.02 NTU, whichever is greater
Infrared light source -- ISO7027 compliant
Easy and quick calibration
TFT Colored Screen (measurement mode, green in calibration) with graphic and text operation guides
U.S. EPA certified, non-toxic, easy-to-use polymer standard solutions
CE certified and comes with 2-Year Warranty
Apera Instruments TN400 Portable Turbidity Meter is built with an infrared light source, using ISO7207 compliant nephelometric method (90°), equipped with a large TFT colored screen, designed for reliable turbidity measurements from 0 to 1000 NTU in various applications both in-field and in-lab e.g. environmental monitoring, water treatment, beverage making, etc.
The test kit comes with 4 vials of high-molecular polymer turbidity standard solutions (0.02 NTU, 20.0 NTU, 100 NTU, 800 NTU), an EPA approved primary standard for calibration of turbidity sensors that is safe, non-toxic and disposable. It is NIST traceable to particle size/distribution and optical density, and its inherent stability means it does not settle from suspension. 
The standards have a guaranteed one-year shelf life even if you've opened the bottle and happened not to have recapped it tightly. The convenient submicron polymer suspensions are non-toxic primary calibration standards approved by the US EPA for drinking water analysis for turbidity.