Length and mass aren't measures of unit. They are just what is being measured. So, they are neither customary or metric. Though, there are customary measures for length and mass, there are also metric measures for these both.
Length customary: feet Length metric: meters
Mass customary: ounces Mass metric: grams
These^^^ are only some examples, there are more measures of units
Though, ton is a measure of weight in the customary system of measurement
