Allen Nut System of Measurement Inch Insert Diameter 1/2 in Overall Length 33/64 in Installed Length Not Applicable Thread Size 5/16 In.-18 Thread Direction Right Hand Thread Type Coarse Flange Diameter Not Applicable Flange Thickness Not Applicable Material Steel Material Grade/Class Grade 2H Finish Black Oxide Body Texture Knurled Compatible Material Metal Drill Bit Size 33/64 in Maximum Hole Diameter 0.516 in Minimum Material Thickness 0.522 in