Operating Viscosity The operating viscosity is needed for any application. We can often determine this, but some applications require that you give us the fluid viscosity. Product specific information Mx Ultra Mag | Generally not required for this meter. V-Cone, Wafer-Cone | Enter the density of the fluid if known,     otherwise we may be able to calculate it for you. Mc Propeller | Meter designed for water or fluids similar to     water in density.