Hex screw heads are of two types—external and internal. Exterior screw heads are hexagonal and protrude from your floor, wanting just like a bolt head. Some hex exterior screw heads have in-built flanges, while some make do While using the hexagon with the head. I had been introduced to them https://typesoflogsiding86407.daneblogger.com/28902283/types-of-screw-heads-uk-an-overview