DEWALT 1/4-in to 1/2-in Socket Adapter in the Socket Adapters department at Lowes.com
1/4 Inch Shank Router Bit Collet Extension Chuck Converter Adapter, Convert 1/2-Inch & 1/4-Inch Shank Bits with ER20 Spring Collet, ER20 M Type Collet Chuck Wrench Spanner -(Pack of 4) - - Amazon.com
Amazon.com: 1-1/2" Male x 1-1/4" Female Thread Reducer Bushing Pipe Fitting, Adapter, Stainless steel SS 304 NPT : Industrial & Scientific