Japanese metal seed beads are beautifully plated over a brass core. The holes are quite large: 11/0s can fit on Superlon, 15/0s have no trouble fitting on heavy (.024) beading wire. They are seamed. We have been using them for several years and haven't noticed wearing, fading, or tarnishing. Please tell us your experience with them by reviewing this product. Size 11/0, 8/0, & 6/0 are in a 2.5x.5x.5 tube (approx. 20, 18, & 15 grams), 15/0s come in 2x.4x.4 (approx. 11 grams).