If your order is for more than 3 prisms; you may qualify for flat-rate shipping discount. Call 888-537-5334 or email us. Genuine replica Deck Prisms from the Charles W. Morgan sailing vessel which is berthed at Mystic Seaport. During a major restoration, 1977-1984, it was discovered that several of the original deck prisms on the ship had been cracked and damaged. Molds were taken from the original 19th century prisms and hand-cast replicas were produced to replace the original. Our deck prisms are still hand cast here in the United States.