The IPT Sink 3 1/2-inch strainer (STRAINER) is made from quality stainless steel and features a twist-to-lock stopper. The IPT Sink strainer prevents food debris and particles from clogging the drainpipe thus saving hundreds of dollars in repairs. If you are installing a garbage disposal, you will NOT need this strainer. If you have a double basin sink and one side has a garbage disposal, then you will need one strainer for the other basin.