YSTD&reg; Groove 90 Degrees Acute Skew-T Fillet Weld Gauge Gage Welding Inspection Test A handy compilation of mathematical relationships between leg length, throats, skew angles and inspe Replaces all other sets of gauges used to measure fillet or groove welds in skewed members at 90 deg To extend or to retract pointer: 1. Loosen knurled thumb screw 2. Depress pointer at press mark until pointer snaps into retract position 3. To extend pointer, reverse procedure