Milímetro cuadrado por segundo

A millimeter squared per second is a unit of viscosity measurement equivalent to 1 centistoke.

For thin liquids like water, oil, or paint kinematic viscometers can be used. The simplest versions feature a cup with an orifice at the bottom. The cup is filled and then a time measurement is taken.

For thicker liquids, a dynamic viscometer can be used. This type of viscometer uses a rotating spindle submerged in sample liquid. This measures the shear stresses as the liquid creates viscous drag. This has the added benefit of measuring a liquid's shear sensitivity.