Unknown British, ‘Reliquary Casket with Scenes from the Martyrdom of Saint Thomas Becket’, ca. 1173–1180, The Metropolitan Museum of Art

other (interior cavity overall): 1 5/16 × 2 9/16 × 1 7/16 in. (3.4 × 6.5 × 3.7 cm)
http://www.metmuseum.org/art/collection/search/464490

Image rights: The Metropolitan Museum of Art (Gift of J. Pierpont Morgan, 1917), licensed under CC0 1.0 Universal

About Unknown British