SK 4940 4 Piece 1/4-Inch Drive Extension and Thumbwheel Ratchet Set 4-piece 1/4-inch drive extension and thumbwheel ratchet set provides improved access to hard-to reach-areas Completely enclosed ratcheting mechanism; easy to remove and replace for cleaning or rebuilding Triple tooth contact provides smooth ratcheting action with little back movement Hardened pawl and teeth for durability and long life; diamond knurled grip offers sure handling 1/4-inch drive