Open back frame. Fill with resin, polymer clay, etc. Or bead it. OD:27.5 x 23.5 x 2.8mm ID:Top section 13.7 x 6.2, Bottom section 20 x 10.5 x 2.8mm Made in U.S.A.. 24mm x 30mm x 3mm Hole size is approx. 2mm (loop). By the each.