What size is the BFL single power supply plug? Im looking to hack an adapter up.

I know cablez makes some sweet adapters but I have everything I need except for the plug specs. Id like to just hit up a local radio shack for it and presto! Im done.

I have made some ATX to barrel plug adapters for my BFL singles......These cables will also fit the Icarus or ztex FPGA or any 12V 2.5/5.5mm DC plug peripheral.  I can also do 2.1/5.5 DC plugs which are found on the x6500.