Item has hex means for securing,hex head is approximately 0.300 in. Deep and 0.253 across flats,item is used for securing bsu-85/b air inflatable retarter,item is 1.00 in. Lg.,0.625 in. Dia.,wt. Is 0.062 lbs,thread is 0.500-20unf-3a,item is packaged as required in accordance with mil-std-2073-1,(item is of steel construction)