This simple, yet effective dipstick provides accurate indication of liquid helium depth. Stainless steel construction with a fine rubber diaphragm, held in place by an ‘O ring over the cup-shaped upper end of the dipstick. The dipstick length is 1.5m. Stainless steel, length: 1.5m The thermal gradient created in the tube leads to thermal oscillations, which are felt by the vibration of the membrane. The frequency of the oscillation with the lower end in liquid helium is noticeably lower in comparison to that when in cold gas, allowing the liquid level to be easily determined (in most cases). The dipstick should not be left in the cryostat when it is not in use because it introduces a large amount of heat.