In my case my faucet was lose. I purchased two shank nut kits. each kit comes with the shank nut and washer. The washer helps secure the faucet to the sink so you do not need to put as much pressure on the plastic nut that keeps the faucet secure to the sink. The hardest part of this was laying under the sink. But it will save you a 100 dollars having a plumber come out to do this for you.