Each ornament is authentically hand-crafted in precise detail, color and design; made of durable, poly-resin that is safe for all aquariums and terrariums; large swim-through chambers provide a comfortable environment for fish to explore. Ornament is 4" x 4" x 5.5" high. Openings are 0.5" x 0.5" high on upper level and 0.75" x 0.875" on the lower level., Manufacturer: BLUE RIBBON PET PRODUCTS INC