The deal runs all day and is only good on single patty Sonic Cheeseburgers at participating Sonic locations.
A Sonic Cheeseburger comes with a beef patty, American cheese, crinkle-cut pickles, chopped onions, shredded lettuce, tomatoes, and a choice of mustard, mayo, or ketchup. They're normally a little over $3 each (you can check out my previous review here)