4pc Ratchet Socket Adapter Reducer Converter Set Tool Kit 1/4" 3/8" 1/2". 4pcs 1/4 3/8 1/2 Drive Socket Adapter Converter Reducer Air Impact Craftsman Socket Wrench Adapter Hand Tools Set BI115+. 1/2 "to 3/8" - (12.5mm square hole to 9.5mm square head) Length: 36mm.