Definitely Aluminum. I tried to scrape off the tinning, couldn't, and also it is way more flexible than even the finest stranded copper I have come across. It says 12 awg on it, but I believe the diameter to be closer to 14awg
Also, for some readers who intend to use this as a battery monitor, there is a load and source side, so it only counts current flowing in one direction.
2 meters and some simple math are needed for monitoring amps in AND out of a battery.
It will however power up the display with voltage hooked to either the source or load side of the leads.
