Sterling silver: A silver charm measuring 18mm. Compatible with: This charm is compatible with other Harry Potter charms, bracelets and necklaces. Charm: Get an official Harry Potter Hogwarts letter clip on charm. Hogwarts letter: The charm symbolises the acceptance letter that Harry Potter receives. Gift: An ideal gift for all Potterheads. Official product: Comes in an official Harry Potter branded box. Hogwarts Letter Clip On Charm | Living Social | Living Social