40 Cavity Black Seedling Tray is a type of gardening tray that is designed for starting seeds and growing seedlings. It is typically made from plastic and features 40 individual cells or compartments that are used to hold individual seeds or small seedlings. Moreover, the size of each individual cell or compartment varies depending on the specific tray, but they are generally around 1-2 inches in diameter and 2-3 inches deep. This size allows for sufficient root growth while also keeping the plants compact and easy to transplant. Also, Tthe black color of the tray helps to absorb heat and promote root growth, which is beneficial for the plants.