These Klutch sockets are specially built for use with thru-hole wrench ratchets. Unique thru-the-hole socket design allows users to fasten or loosen longer bolts in tight areas. Durable chrome molybdenum construction in popular metric sizes. Adapters qty. 0, Material Type Chrome molybdenum, Pieces qty. 10, Storage Type Plastic case, Metric Socket Size mm 8, 10, 12, 13, 14, 15, 16, 18, 19, 21.