PM706E-DG Brass Inage (Sounding) Plumb Bob with Deep Grooves
Solid brass 7/8" square x 6-3/4" long overall with tapered point and phenolic black plastic scale graduated to 16ths, accurate to within 1/32", with zero calibration point at the bottom of the bob. Deep grooves along side of scale
Designed to be used with inage, sounding measuring tapes to measure the depth of liquid in a tank from the surface of the liquid to the tank bottom. They have grooves on the brass side adjacent to the phenolic scale as recommended by API.