The MILWAUKEE INSIDER Box Ratchet 1/4" Anvil Adapter is designed to uniquely fit into the M12 FUEL INSIDER Box Ratchet allowing the use of existing 1/4" drive sockets and protecting the investment you've already made while delivering on performance and productivity. INSIDER Box Ratchet Adapters are available in ¼�, 3/8�, ½� ¼� Hex, providing Ultimate Versatility.