Designed to fit Storex Letter Size Storage Trays, 3-inch deep and 5-inch deep versions. The storage trays are designed to neatly organize all your letter-sized handouts, booklets and papers. The bright colors are ideal for STEM or STEAM organization. The easy-to-grip comfort edges are perfectly sized for big and small hands. Made of nonporous plastic, the trays and lids are dishwasher safe and drop resistant. Trays sold separately.