It is customary.
Yards are measured in the customary system, which is primarily used in the United States. In this system, one yard is equivalent to three feet or 36 inches. The metric system, on the other hand, uses meters as its primary unit of length.
It is a customary unit.
The opposing systems are imperial and metric, not customary. But, meters are metric.
The pound is NOT a metric unit.
It can be more or less. An once (customary) is bigger than a gram (metric) but a pound (customary) is smaller than a kilogram (metric).
Metric.
Metric
Metric.
A "gran" is a German measurement, it is neither customary or metric. A "gram" is a metric unit.
It is a customary unit.
customary
I'm guessing by customary, you mean imperial. if so inches are customary/imperial