You will never hear Brian Berger, CEO of men’s underwear retailer Mack Weldon, apologize for the limitations of selling intimate apparel online. Quite the opposite, in fact: “Our whole business is formulated on the idea that the best way to buy the things we sell is not in a physical store,” said Berger. The success of the business, which Berger co-founded with Michael Isaacman in 2012, supports his belief. Mack Weldon has been more than doubling its business year-over-year and boasts a customer base of more than 250,000. The brand is adding well over 15,000 new customers each month and maintaining high loyalty rates: 20% of new customers return within 60 days, and they spend, on average, 40% more than they did on their initial visit.