The Column is a crystal-clear oil level sight glass that allows you to visually inspect the condition and level of oil in pumps, gearboxes, storage tanks and reservoirs. It features a one-piece design with 1-inch NPT threads at each end and includes a 3-micron breather. The Column can also be plumbed to vent back into the equipment's head space. Two tamper-proof level rings mark the idle and running oil level. Each ring is made of durable polycarbonate and secured in place with a hex screw.