Increase your tomato yields by 40%. Red light is reflected off these trays to stimulate plant growth. Like the Automators we offered for years (which this item replaces), the trays protect against cutworms, blossom end rot is reduced, they serve as a mulch to prevent weed growth and they help roots retain consistent moisture. Made of durable plastic. Measures 12 inches square. Use with all your tomato, pepper and vine plants.