It's primarily designed to be used in non-corrosive water-based liquids and dry fluids (powders). It does away with clunky mechanical floats, and easily interfaces with electronic control systems.
The eTape sensor's envelope is compressed by the hydrostatic pressure of the fluid in which it is immersed. This results in a change in resistance that corresponds to the distance from the top of the sensor to the surface of the fluid.
The sensor's resistive output is inversely proportional to the height of the liquid: the lower the liquid level, the higher the output resistance; the higher the liquid level, the lower the output resistance. Due to its internal geometry, the resistance value can change by height level increments of 1/32 inch (0.79 mm).