A: Convenience and compatibility. Porphis mixing accessories — viscosity cups, mixing sticks, strainers — are sized and calibrated for the material volumes and viscosity ranges relevant to the spray guns in our lineup. A viscosity cup calibrated to DIN4 standards gives you consistent measurement results that correlate directly to the pressure and fluid settings in our gun specifications. Hardware store mixing tools vary in calibration and material — using the same reference standard across your measurement tools and your gun settings removes one variable from an already complex process.