Iron Bead Tips, Calotte Ends, Clamshell Knot Cover, Nickel Free, Antique BronzeSize: about 4mm wide, 8mm long, 3mm inner diameter, hole: 1.5mm.These Bead Tips, Calotte Ends, Clamshell Knot Cover are used to conceal knots at the ends of beaded strands and to connect the strands to the clasp.