A general definition of Turbidity is the decrease in the transparency of a liquid caused by the presence of un-dissolved substances (ISO/EN7027). The definition of Turbidity Measurement can explained as where Solids are so finely dispersed in the liquid that they do not significantly settle even when allowed to stand for a long period of time.

Turbidity meter,Handheld, White Light, 0-1100 NTU
QT20000
Turbidity meter, Handheld, Infrared Light, 0-1100 NTU
QT20008
Turbidity meter, MTOL+, Lab, White Light, 0-4000 NTU
QT28060