The Plastic Tray is a great option if you are not going to use the functional cardboard box or wooden sleeve. The tray is designed to accommodate the  dog grass pee pad (24" x 16").  The grass is easily removed from the cardboard box and inserted in the plastic tray. 

The tray is helpful if:

1.  Your dog chews on the cardboard box

2.  Your Fresh Patch is being used outdoors in rain or snow

3.  Your dog needs a lower profile for entrance into the unit