This is a custom manufactured set of fluid level cups.

This is a system of interconnected cups filled with fluid, a depth micrometer is used to calculate height differentials by measuring the distance from the fixed cup's rim to the fluid surface.

This system offers high accuracy over long distances where a line of sight is not available. I used this system to level a large gantry milling table (80 ft X 16 ft) to a laser verified flatness of .008" across the entire table.