What is this suggestion related to (eg. Website / Launcher / The game itself / etc. ): Game
If im not mistaken, red item slots icon means that the armor piece is already broken(0/150 for instance). I suggest to make an yellow indicator if the armor piece is 30% durability(50/150 for instance). The indicator is already in the game, so making yellow indicator at 30% durability is the same as buff duration information. This way players can prepare(just as if its any buff that expires).