Medieval buckles were made of iron, copper alloy, pewter, gold, silver, and occasionally bone, and of all these the iron buckles are generally the largest, plainest and most numerous. Some do, however, have decorative grooves or shaping, and a substantial number retain traces of nonferrous plating, probably tinning. Iron buckles K1–274, many of which retain their pins, and some their buckle plates, have been classified according to their frame shapes. They are grouped chronologically within each type.