A suction cup, also known as a sucker, is an object that uses the negative fluid pressure of air or water to adhere to nonporous surfaces, creating a partial vacuum. Suction cups are peripherial traits of some animals such as octopuses and squids, and have been reproduced artificially for numerous purposes in this case to they're used on the bottom of the Medline leg extensions to give you a secure base for your bathroom safety equipment & accessories.