Help with a 2003 Chevy

OK, I have a 2003 Chevy Caveiler. I need to brakes on it. It went to Chevy Service and parts to ask what size allen key wrench I need to take the Calibers off. Chevy won't tell me. I know there are books out there but, I don't have the ezxtra $$ to buy them. Can anyonetell me what size it is? or where I can go to look it up for free?
Thank you all so much.
vic

The easiest answer is, buy an allen set. They're $10

I believe most modern chevy allen setups are 10mm

I think my 1990 had 3/8 allens.

Just buy a whole set.