The JW Insight Clean Cup keeps food and debris from falling outside the cage. Place the shield and the cup a few inches into the cage to prevent the bird from shoveling out his seed onto the floor. Because it is clear, birds don't mind sticking their heads into it (unlike opaque shields).Unique washer system makes it a breeze to fit all size and style cagesEasy to clean and dishwasher safe tooScrews into the horizontal and vertical bar cages to guaranty a secure fitThe Clean Cup Base Comes in Assorted ColorsSmall Clean Cup: 2"W x 3"HMedium Clean Cup: 3"W x 5.5"H