Features:For checking the squareness of an edge, using the light-gap method; The blade is bevelled on both sides,30 degree edgeSquare is true right angles both inside and outsideBeams and blades are ground and lapped for parallelismMachinist square supplied in a sturdy protective case1.For checking the squareness of an edge, using the light-gap method. The blade is bevelled on both sides.2. Accuracy grade 1, squareness tolerance of 0.02-0.05 mm.3. Supplied in a protective case.4. Beams and blades are ground and lapped for parallelism.5. 30 Knife edge, beams and blades are ground and lapped.specification:Size: 80x50mm/125x80mm/63x40mmEdge angle: 30 Seat Width: 5mmAccuracy: Grade 1Tolerance 0.02-0.05 mmUse For: 90 right angle measuring, designed for precision layout and measurement work.Color:sliverMaterial:stainless steelQuantity:1pcNote:Please allow 0-1cm error due to manual measurement. pls make sure you do not mind before you bid.Package includes:1x 90 Degree Right Angle Ruler