Open back frame. Fill with resin, polymer clay, etc. Or bead it. OD:27.5 x 23.5 x 2.8mm, ID:Top section 11mm Dia, Bottom section 20 x 5 x 2.8mm Made in U.S.A.. 24mm x 30mm x 3mm Hole size is approx. 2mm (loop). By the each.