Boys Ben 10 Action Bedding Sheets Set (Twin Bed) (Green) Please note: This product is a UK import, the sheets supplied are slightly smaller than the standard US duvet size, it will fit but the duvet may fold at the edge when covered. This is not a comforter but sheets for a duvet. High quality girls bedding set. Fiber: 50% Polyester and 50% Cotton. Size - Duvet sheet: 53 x 79 inches.