EK's GPU Fittings Question

[Tooterfish]

I need to liquid cool my GPU's. I've picked the blocks on EK's site but I'm required to buy the fittings. My tubing is 3/8" ID 1/2" OD acrylic. Can someone explain to me how I'm supposed to pair GPU fittings with my tubing? These are my avilable options http://imgur.com/a/EpYyo, none are 1/2"OD which is how far my experience takes me (pick the 1/2" fittings). I'm assuming I need 10/13, so if anyone can confirm I would really appreciate it!

Just got off phone with support, it appears I was right.

Thanks