Need help with pfister faucet

Please help, been stuck on this for months :,)

We took out our old aerator, big problem. We don't know what to replace it with. I looked on the site recently for the part I think goes with the sink but I'm pretty sure it's out of stock. Please help!

Pretty sure it's this faucet -> https://www.pfisterfaucets.com/bathroom/product/penn-lf-042-1pe-single-control-bathroom-faucet