Compared to standard hex bolts, square bolts have a greater surface in contact with the part being fastened, and therefore provide greater resistance to loosening (though also greater resistance to tightening). Square bolts are typically mated with square-headed nuts.
. A machine screw, also called a stove bolt, is generally a smaller fastener threaded the entire length of its shank.Machine screws are used in fastening nearly all types of hard materials.