From Tovolo.

These sink stoppers and strainers add a touch of color to your kitchen and conveniently collapse for easy storage. The strainer function traps food and debris while letting the water flow through.

To use the stopper function just turn the knob to drop the stopper and prevent the water from going down the drain. You can empty the sink easily by pulling on the center post.

These stoppers and strainers contain silicone, are BPA free, and are easy to clean and are stain resistant.