20-row seedling flats fit perfectly in these sturdy trays, allowing them to be well supported and drain freely. They can also be used for microgreens, allowing you to save on growing media costs. The same dimensions as our white Shallow Leakproof Trays, but black so you can easily tell them apart. Outside dimensions: 10.8 x 21.25"; 1.3" deep. Compatibility: Use with 20-row Seed Flats, Soil Block Propagation Trays, and Plug Flats. Not compatible with Jumbo Plug Flats or Pro-Trays.