Super Sprouter Celled Plug Insert - 10x20With Super Sprouter it's easy to find the exact inserts you want to use with your starts. From square, to circle, to their patent pending star patter, there is the perfect shape to go with a combination of grow media. If you were looking to mix and match your starts, there is even a tear away option to make propagation as easy as possible. All Trays will fit your standard 10x20 propagation tray.