Oops, I guess I jumped to the conclusion that this one in Elite Element’s display
https://www.ebay.com/itm/173058142084
is the same as the one in this thread here: https://forums.goodsamclub.com/index.cfm/fuseaction/thread/tid/29798122.cfm
The display and current sensors do look identical.
The ebay one does say the current sensor is a "through the hole current transformer" but I haven't heard of a transformer that works on DC so I figure it must be a Hall Effect sensor that measures the strength of the magnetic field around the current by its influence on electrons flowing in a semiconductor.
I find Elite Element a quality and low cost provider of LED and battery monitor products. However I bought my wireless Hall Effect monitor from Amazon for fast delivery and the thread here reviewing it. https://forums.goodsamclub.com/index.cfm/fuseaction/thread/tid/29798122.cfm