The new revolutionary U.S. EPA-accepted ProCal primary turbidity standards manufactured by HF scientific are safe, easy to use and certified for use not only in HF scientific instruments but in many other manufacturer’s turbidimeters, including the Hach 1720 c/d/e process series and 2100 series of laboratory and portable instruments. To see how they can work for you, visit the website at www.hfscientific.com.