Take the guesswork out of measuring. When you want to know exactly how much product you have in your drum, use a gauge. There are many options to drum gauges.
Have a horizontal drum? Use a Calibrated Sight Gauge. Use this gauge with a 3/4″ NPT faucet for continuous gauging and dispensing (faucet is not included). There is a Standard, a Stainless, or a PVC version for your different gauge needs.