How can I have 2 leftBarButtonItems in iPhone app, and 1 be the default back button?

I would like 2 leftBarButtonItems, but leave one of the items as the default back button for Navigation Controllers. I have set up: self.navigationItem.leftBarButtonItems = [NSArray arrayWithObjects:archives, ???, nil]; where archives is a UIBarButtonItem I created, but do not know what the default back button is to include in the array. Any suggestions?