Celtic Heroes

Does anyone know exactly how much concentration they save? I haven't found anyone talking about it before, they give (Resist Fishing: 20) and we are told in the description that it reduces the rate at which concentration drops. But I recently got a second one and I realised I wasn't even sure how the first one worked, do two of them stack? Does 20 resist fishing just mean you save 20 concentration per reel in or is it 20% in general? Or is it some other calculation? I couldn't find a single post talking about this I'm super interested in finding out

Pools of water deal fishing damage to the players concentration bar.

But I would imagine the rate of damage reduction is the same as it is with all other forms of damage/resistance.

Meaning it is likely an exponential increase/decrease.

Not a flat amount or as simply as percentage based.