D&D: The Xanathar Beholder Gamer Pouch - Rules of Play says:

Love him or fear him, the Xanathar craves power and flattery over all things! This comfy pouch, sized to fit dice and/or other small accessories, is made of soft plush material. A heavy duty zippered pouch on the inside is perfect for gaming dice, tokens or anything else! The Xanathar Beholder comes with a carabiner style attachable hook for storage on the go!