Western Instruments N88-4 Pocket Pit Depth Gauge, 1.5 Dual Edge Reversible Blade. Western Instruments Pit Depth Gauges assure compliance with vessel, pipeline, tank and OCTG specifications for corrosion and erosion depth measurement. Measuring Range: 0.0-0.5 (0.0 – 12.7 mm). Resolution: 0.001 (0.01 mm). Dial Diameter: 1.4 (35.5 mm). Center-mount 1.5 (38 mm) Dual Edge Blade (Reversible). Available with dial or digital indicators. Western Instruments Pit Depth Gauges allow the Corrosion Inspector to conveniently measure Pit Depth or material loss in areas of Weight-Loss Corrosion. Various Blades for the Pit Gauges are available for different applications, including the Bridging Pit Gauge which permits Inspectors to Span or Cantilever over large areas of Weight-Loss Corrosion, to get a true measure of Pit Dept lineKit Contents line. Western Instruments N88-4 Pocket Pit Gauge Digital Indicator. Dual Edge Blade (reversible), 1.5 (38mm) long. Carrying Case line Features. The vertical position of the Contact Point, needs to be Zeroed with respect to the Knife Edge of the Blade. Zeroing can be accomplished in two ways; by adjusting the Height of the Dial Indicator in the Blade; or by Rotating the outer Bezel Scale while pressing on the Plunger onto a flat surface. To quickly check the Zero Point of the Dial indicator, place the Blade on a representative smooth surface. Gently press the Plunger, until the contact point touches the surface. While the contact point is on the surface, loosen the Bezel Lock, and rotate the Bezel Scale until it reads’0′ with respect to the pointer. Loosen the Fastener(s) holding the Dial Indicator in place. Hold the Blade firmly on a Flat Surface, and gently press the body of the Dial Indicator down until the contact point touches the flat surface. Carefully re-tighten the Clamp Fastener(s) or the Set Screw. Any fine zeroing can be done by rotating Bezel Scale on the Indicator. Height Zeroing should be done, whenever the unit is put into to use. Zeroing a Digital Indicator. Digital Indicators can be Height Zeroed or Positioned in the same way as a Mechanical Dial Indicator. To Zero the Digital Indicator simply press the Zero Button when the Contact Point is on a reference point. If the Digital Indicator is Height Zeroed, press Zero when the Plunger is fully retracted. To select Metric or Imperial Measurement, simply press the mm/in Button. Whennot in use, press the On/Off Button to turn the Indicator off. The position (or rotation) of the Dial indicator can be changed by simply loosening the Clamp Fasteners or Set Screw, and rotate the Dial Indicator about the Blade. After the Dial Indicator is rotated, the unit should be Dial Zeroed.