Look at Calb cells here http://www.*********/
Your experience may be different.
My one and only dealing with them left me completely unimpressed with their lack of professionalism, their lies and misrepresentations, and ultimately an "oops" email sent by one of their staff to another that accidently included me.
I'd go so far as to say "dishonest", and I have gone out of my way to find stuff that never touches their grubby paws.
Strong words, but I've got the email trail to back it up.
To bring it back on track... under and over voltage "protection" is a failure device I chose to do without.
My inverter and charge controllers prevent over-voltage, and a backup monitoring-only system would alert me anyway. Under-voltage isn't likely to happen, since my inverter will call for a generator run if SoC gets low, OR voltage gets low, and even if the generator didn't kick in, the inverter low-voltage cutout is above the batteries minimum safe voltage.
I do however monitor individual cell voltages, which I find far more useful anyway.