Joe, "good purchase" for what? Buying random items judging only by their description - this isn't going to work. Too much junk out there. Or misleading advertising - can be a good item but not for what you need.
You've found a 10W solar "kit" with lengthy description of how it would power everything - bullchit.
Now you've found this "battery monitor" - this is a voltmeter, not any "monitor". Maybe you don't need a "monitor" - I don't. But I do have a voltmeter, and ammeter built-in in my solar charger, and a few other things.
What are you trying to assemble - a cheap portable solar for camping? Or something else?