Hex exterior- External hex screws need a compatible wrench or socket to setup. This type of generate recess will get excellent leverage because you change the full generate from the perimeters of the screw. This bolt, along with the machine screw that goes with it, sits on one particular facet https://types-of-log-siding17395.get-blogging.com/29869164/the-ultimate-guide-to-types-of-screw-heads-chart