Wiring Harness for AR 4201 or AR 6201 Aircraft Radio
This wiring harness is highly recommended.  It makes it very easy to install the radio and connect it to the Becker-1PL042 Speaker and Wiring Junction Box.  All connections are labeled and color coded.  This not only makes installation fast and error-free, but also makes long term maintenance much easier. 
Length: 12 feet (3.66 m)

Note: Becker's price for this item is a bit outrageous. I offer an equally good Goddard version: Cable-Becker-AR6201-SpBox-3