Easy to use:
(1) Place the tool on the first piano wire segment,
(2) Rotate the vial leveling screw to center the air bubble,
(3) Place tool on second piano wire segment,
(4) Observe which direction the air bubble has traveled, and count how many lines it has crossed.
Also used for plate & bridge height adjustments, glidebolt adjustments, calculation of downbearing force in pounds.
