Most truss rods, (on Asian instruments), are 4mm hex keys. At least that's the case with the 2 Ibbys a Crafter, and a Fender I have. (An AEL10 & EW20, D-8-12-LH, & a "Sonoran").

Here's the StewMac page for truss rod wrenches: http://www.stewmac.com/shop/Tools/Wrenches/Gripper_Truss_Rod_Wrenches.html?actn=100101&xst=3&xsr=7580

If you're not too proud or a guitar snob, it's off to either Pep Boys or Sears with you.
I have to say, If you have to ask that question, I hope you know what you are doing.

More guitars have been ruined by wrong truss rod adjustments than bar room fights.

I'm not supposing you don't know, I'm mearly cautioning. If you need help ask the question.