By pulling a pin - you can go from zero to 1 ft. vertical offset in seconds for clearance under rod. Measurements are more accurate because you are measuring with a vertically plumb rod. Made for Crain 25 ft. SVR rods. Made of lightweight nonrusting aircraft aluminum. No tools needed to attach to rod. Slides on and off rod in seconds. 24˝ measuring arm can be extended to36˝by adding 1ft extension. New round foot design slices through material at bottom of pipe and insures accurate invert and pipe diameter measurement.
