Harry Potter Whomping Willow Sterling Silver Slider Charm with Swarovski Crystals Elements This charm has been created using the official style guide from Warner Bros. It is approx 15 mm in height and 15 mm wide. This charm comes in the official Harry Potter branded box and shows the Warner Bros logo on the reverse. This charm is compatible with our Sterling Silver Harry Potter Slider Charm Bracelet. The Carat Shop are the official licensed manufacturers of Harry Potter Jewellery on behalf of Warner Bros.