73 Brake line

[FLG]

Hey guys,

Had my 73 a little over a month now and it seems to have a beef with me lately 

The brake line that runs along under the driver side door decided it wanted to finally rot through this evening (thankfully while i was parking) and only caused me to give the guy in front of me a little tap. Anyways, i figure id ask you guys what size it is? Would make it easier because i have some spare brake line laying around, if its the right size i wont have to run around tomorrow. The rest of the lines have been changed, but i guess the previous owner decided that this one was fine