The Oil Sight Glass Level Monitor (OSGL) allows you to view oil color, clarity and accumulation of water or other contaminants while monitoring the level of the oil in the reservoir. It is available in multiple lengths ranging from 3″ to 24″ to correspond to the distance from the oil reservoir access port and the maximum height the oil will reach. A dual port version is available with a second 3/8″ NPT port opposite the installation nipple to allow the installation of a sampling tube to draw representative oil samples without pulling outside contaminants.