Plastic canvas sheet in various counts and sizes. 
 
14 count - 8.5" x 11" (21cm x 28cm)
10 count - 10.5" x 13.5" (27cm x 34.5cm)
7 count small - 10.5" x 13.5" (27cm x 34.5cm)
7 count large - 23.5" x 13.5" (57cm x 34.5cm)