Full-grain leather comprises the top grain layer, which contains the highest percentage of fibers, making it the most durable part of the leather. With grained leather, the top layer (about the thickness of a banknote) is sanded down as there are usually imperfections. this top layer. This is called premium leather because the top layer is removed (makes no sense, right?). Therefore, full grain is the best choice for a belt because you need strength when it comes to a belt with a top layer. If you see 100% leather or real leather, it is not full grain leather. This full-grain leather strap is thick and definitely looks like it will stand the test of time (I wear the strap every day, unless I'm in a bathing suit all day or I'm sick in bed (extremely rare)).