Bosch 2610906284 1/2" Collet Chuck For 1613-,1617-, 1618- &
1/2 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
763622-4 Makita Collet Cone for 1/2" Routers
Big Horn 1/4″ Router Collet for Porter Cable | The Woodsmith Store