20. This would be the floor section for the driver side for the 1953-55s. It has the cutout for the stock fuel tank sender access. It's nice that the small hole that used to be master cylinder access is covered. All aftermarket brake systems used today do not need this access anymore. I usually cut a piece of sheetmetal to fit the hole, paint it black, and silicon it to the floor. Mid Fifty also sells the proper cover if that's what you would like.