This is an 8-pack of 9/16" (inside diameter) nickel grommets with matching washers. Grommets are commonly used in canvas work, leather work and other cloth-related work, but they also make great decorative hole inserts for various craft projects including cigar box guitars! These grommets are intended to be used with hand tools, if you are using them for cloth/leather work. They are not self-piercing. The 5/8" shown in the listing photo is the OUTSIDE DIAMETER of the shaft portion.