The measurement listed is the diameter of the base of the plug. Use flathead plugs to cover unsightly screw heads in furniture, floors and wood working projects or as accents in crafts. This package of unfinished hardwood flathead plugs are easily installed with wood glue and finished with stain or paint. From the single button used as a train headlight to the thousands used to finish that new floor, we guarantee you will find Stockade buttons and plugs equal to or superior to any other available today. Note: wood species is birch or maple depending upon supply.