If you have the Aspect 420 bird feeder, then this seed tray is a must. It attaches very simply and you don't have to remove it to use the quick release feature at the bottom of the feeder to clean it. So simple. My cardinals, especially, feed naturally from this tray. No more tons of seeds falling on the ground...which makes my raccoons and squirrels unhappy. Truly, this is a must-have.