If you're asking if they exist. Yes they do. They are usually called Copper (15mm or 22mm) to 7lb Lead. It is called 7lb lead because each yard of copper used to weigh 7lb (pounds). You can get this adaptor but they are quite expensive and comprises of two compression fittings, one each end.
A gallon is certainly not metric. It is imperial.
Imperial.
Acre is an imperial measurment. Hectacre would be an analogous metric measurment.
Metric tons can't be converted to imperial gallons. Metric tons measure mass, while imperial gallons measure volume.
There is no such thing as a metric gallon. The metric measurement is litres. There are 4.54609188 litres to an imperial gallon.
adaptor - a fitting used to connect different pipes
A tonne is a metric measurement.
imperial - Elvinusa
English and Metric
The opposing systems are imperial and metric, not customary. But, meters are metric.
I'm guessing by customary, you mean imperial. if so inches are customary/imperial
No. It is imperial.