Solid wood trays with contrasting dark blue laminate bottom to make letters and tracings stand out clearly. Includes lid and fine grain Safe Sand®, free of crystalline silica. Grades PreK-2. Also a great item for special needs. Letter Formation Sand Tray is 8" x 8" - Great for letter practice. Word Formation Sand Tray is 15" x 8" - Great for tracing words. Jumbo Sand Tray 18" x 18" - Great for tracing letters, words and make believe adventures with favorite toys and manipulatives.