Hi! We just received a new vessel sink which didn't come with any installation instructions. The popup drain has several pieces to it and though we think we know how it all goes together, there is one ring which is a soft foam we're not sure if that goes above or below the sink... or if it's maybe just packing material! I'm attaching a photo here to show where it is on the drain assembly. Can anyone confirm where this should go? Thank you for any assistance!