This is .175" (4.5mm) diameter ball chain, with 49 balls per foot. Use it to create fantastic designs in your mosaics! When you grout, the connectors between each ball disappear in the grout & you're left with what appears to look more like a line of little black beads. It's a very fun way to add texture & a whole new look to your artwork! Hover over the 2nd image to see this color used in a completed project.