The amp meter comming with 75mva shunt resistor,witch is included in the pack. It is very simple for installation .
Installation is very simple.There is only four coloured wires from the meter,and they needs to be connected to the shunt resistor to read the loads.
The wiring diagram will be provided us well. It is compatible with any 12V vehicles such all types of cars and vans,and also can read the load if is build on 24V vehicles like a Trucks and buses.
It is a highly recommended gadget for your hho project.