11/0 is considered the standard-sized seed bead. They are larger than 15/0 beads, and smaller than 8/0 beads.
Silver Lined Beads are not washable.
15/0 is 1.5mm 11/0 STANDARD is 2.1mm 11/0 DELICA is 1.6mm. 8/0 is 3.0mm