Internal single purpose HI-LO Small Height Gauge welding gage Ruler Root gap in METRICFor more measuring tools, please click here! Product Name: HI LO Welding Gage Internal Single Purpose Gauge Welding Ruler Root Gap Metric Descriptions: You can check the internal alignment of you fit up quickly with the Hi Lo gauge 1. Unlock the retaining screw. press the gauge legs beyond the barrel 2. Insert the legs (wired) into the root gap space or the two pieces of pipe to be fitted, turn the gauge 90, being careful to apply a constant back