They are the sharpest, smoothest pins made. They bend, but don't break. These have thinnest shaft of any pin. Glass heads won't melt when ironed over. .50mm steel shaft. Red heads are easier to see on white and light colored fabrics. Glass head silk pins are great to use for marking or decorating on your sewing or crafting project. These pins never snag or leave holes in your fabric. With colored glass heads, the pins are easier to find and you can iron over them. These super fine pins have a .50mm steel shaft and come in a sturdy plastic box with a clear lid. Red 1 3/8" 250 pc.