block hook for sale, brand-new and used.

Fast, accurate wire and valve locating...the choice of electricians and  irrigation professionals The 521 combines adjustable transmitter power with a sensitive locating receiver to allow location of buried wires and valves with speed and confidence The first thing is that there are basically two functions: tracking wires and finding valves. To track a wire path, you attach the red lead from the tracker to a valve hot wire or the common wire.