i have the smaller one of these DRO, just one
is work well but i guess is just luck to get a perfect unit or a, lets say, half good one
the one i have is a 6", buy from Grizzly, works good, but in the short time i have used (just a couple of hours like max) it turn on alone, and lose the zero reading, that pass me a few times, at first, i believe that the vibrations from the machine was causing the batteries to move and disconnecting, causing a reset to the unit
but soon figured out that te vibration was not the problem, the batteries are hold tight in the slots, and the DRO turn on without running the machine or machining.
other thing that happens (not more) is that the display got freeze, measuring nothing, i have to take out the batteries for 30 sec to fix that.
i only have used for a couple of hours, but all that problems that shows in the begining, now seems to be right.
i have to remark that im using the DRO with the batteries that come in the box, four identical batteries were supplied, so im using two of these
i do not discart the posibility that these batteries maybe are not the best, or come semi charged, or discharged, maybe that was causing my DRO to not function properly. is higly probable, but i do not have a way to prove (i dont have others batteries that fix the unit, besides the other two that come in the box)
but are people that this DRO is working great, and some other like i, i suppose, that are still evaluating this unit. maybe just luck
i hope that this comment would help
Saludos