The benkelman beam is a simple lever arm device. It measures deflection of flexible pavements under the action of moving wheel loads. Place a probe beam between the tires of a test vehicle. The vehicle passes over the test area to beyond the end of the probe beam determines deflection measurement. The reference beam has a leveling adjustment to zero the dial indicator. A switchable battery-operated vibrator serves as a personnel alert and assures free movement of beam parts during measurements. The three-piece, anodized, lightweight aluminum beam is 33lb net weight for easy portability, and the longest piece is 6.5ft. Dial indicator sold separately.