Prym Cover button blanks. Made of stainless metal and a stable wire eyelet are available in sizes between 11 mm and 38 mm.. A gearwheel on the inside helps the fabric stretch evenly. The back of the packaging has illustrated instructions in three steps on how it works. A cutting template is also illustrated for cutting a circle in the fabric. Depending on the textile used, the finished buttons can be washed at up to 60 degrees. 15mm without tool 6pc.