Those will certainly tell you battery voltage, and give you a better idea of the state of your battery than the three idiot lights.
I put in a DROK one that also has a clock and a thermometer, along with an ammeter so I can see the charge or discharge current. For my needs, it's worked out very nicely. (If you get an ammeter, be aware that many cannot work bidirectionally, and many of those that can require an isolated power supply to do so. I put in a little isolated DC-DC voltage converter chip to power the ammeter.)
