The deal is good on single-patty (quarter-pound) Sonic Cheeseburgers only at participating Sonic locations.
Sonic Cheeseburgers include a beef patty, American cheese, chopped onions, crinkle-cut pickles, shredded lettuce, tomatoes, and a choice of ketchup, mustard, and/or mayo. They are regularly about $3.29 each (may vary).