Missing the rubber piece that fits over the stay buttons on the faucet. It was not on the faucet sprayer or in the box. We have already installed everything, just need that small piece.

Contact where you got it from, or the contact number in the installation or instruction manual/booklet.

That looks like a Hampton Bay SKU--Home Depot?

I am sure it fell out of the sprayer during transport. Call manufacturer. They will ship you one for free

Milo