Deerstalker Hat. Put the hat on! According to Dr. John Watson in Season 3 of Sherlock, the detectives distinctive hat makes him famous. Whether youre hunting for deer, clues or fame, it keeps sun, rain and snow off your face and the back of your neck. Lower the side flaps, and it warms your ears, too. Irish wool herringbone tweed, handcrafted by a third-generation family company in County Donegal, Ireland. Sizes M, L and XL - M (22⅞ʺ to 23¼ʺ), L (23⅝ʺ to 24ʺ) and XL (24⅜ʺ to 24¾ʺ).