Install the Basket Strainer
Apply a ring of plumber's putty under the lip of the new basket strainer flange. Fit the strainer into the sink opening and make sure it is centered.
Under the sink, place the rubber washer onto the strainer flange, followed by the bottom mounting cup, then thread on the mounting nut. Using pliers, tighten the mounting nut until it is firm.
Remove the excess putty that oozes out from the strainer lip, on the top side of the sink.