Help: Explain "increased Armour Rating during Effect" to me please

From my understanding of Maxroll guide.

I dont need the flask to be active to have the effect active?

"

Important note: Flask Suffixes such as 50% increased Armour during effect provide the same benefit regardless of which flask they are on. This provides flexibility during crafting.

but when I running maps. I realise when my other flask is poping off. I dont gain the extra armour.

Sorry I am a total noob

That note just means that it does not matter what type of flask the mod is on. It does not have to be on your Granite or Basalt flask. You can have the increased armor mod on a Jade flask or a Sulphur flask. But the flask does have to be in use to get the effect. Now you do want the flask with increased armor mod to be in use at the same time as your armor flask in order to get the most benefit.

For example, I have increased armor on my Jade flask, increased resistances on my Granite flask, increased evasion on my Sulphur flask and reduced curse effect on my Quicksilver flask. Since my flasks are always in effect, it does not matter which flask as which mod.