The Ohio State football team awards helmet stickers resembling buckeye leaves to players for exceptional play. The stickers represent the leaves of the buckeye, a species of tree native to North America. Each player receives a sticker for a win, two stickers for a win in a conference game, and three stickers for a win over Michigan. Players also get stickers for individual performance or unit achievements. For example, the Buckeyes defense receives a sticker if they rack up at least five three-and-outs, and the Buckeyes' offense receives a sticker upon executing 10 plays which gain 12 or more yards. The criteria for receiving a buckeye has been refined over the years, and Coach Jim Tressel favors a teamwork approach over an individual-based award system.