It achieves this action by using a flanged nut inside a specially shaped dished-out washer.

Unscrew the large flat flange nuts from around the shanks.

Swivel flange nuts are mostly used in joining wood and plastic.

A flange nut is a nut with an integral fixed washer.

It achieves this action by using a flanged nut inside a specially shaped dished-out washer.

Fasten the faucet by sliding underneath the sink again and attaching the new flange nuts to the shanks.

Fasten the faucet from underneath by attaching it to the shanks' new flange nuts, which are supplied with the faucets.

Serrated flange nut

Flange nut (collar nut)

A flange nut is a nut that has a wide flange at one end that acts as an integrated, non-spinning washer.

These are usually shaped as either a rectangle, a flange nut, or a hex nut; the rectangular speed nut is also known as a flat-style speed nut.

The flange nuts are sometimes provided with a swivel flange which helps in creating a more stable structure without affecting finished product like a serrated flange nut.