Under Armour. According to CEO Kevin Plank, the added the “u” because it gave them an easier phone number. “The reason we added the ‘U’ in ‘Armour’ is that I was skeptical at the time about whether this whole internet thing would stick,” Plank told The Post. “So I thought the phone number 888-4ARMOUR was much more compelling than 888-44ARMOR. I wish there was a little more science or an entire marketing study behind it, but it was that simple.”