Twins Mary-Kate and Ashley Olsen haven't been together on TV in years, but they're taking to YouTube in joint ads for their new website, StyleMint.

The 25-year-old sisters are running a competition to win T-shirts on the site, which advertises that customers can "get styled with exclusively designed T-shirts by Mary-Kate Olsen and Ashley Olsen."

Mary-Kate and Ash are taking this site seriously -- even if it is just T-shirts! "It took us a year-and-a-half to make the first T-shirt," Mary-Kate said.