Barrel plug size

What size barrel plug is on the end of the power cable? I need to make a power cable for a 12v source, and so far neither 5.5mm x 2.5mm nor 5.5mm x 2.1mm plugs have fit. Thanks!
Hello, I also have the same question regarding power specifications. I have a Minix Neo J50C-4 and a Neo J50C-4-Plus that I need to build power cables to run then on 12 volts from a RigRunner Power distribution switch. I will use Anderson Powerpole connectors on the RigRunner end but what are the requirements for the Neo plug and polarity?

Thank you