Tarnish Resistant Smooth 304 Stainless Steel Magnetic Clasps with Glue-in Ends, ColumnSize: about 13.5mm wide, 21mm long, hole: 8mm.These Smooth 304 Stainless Steel beads with smooth appearance are special. They are well clean and never rust. And they are the best beads for multi-strand necklaces. And they are affordable.