they will definetely rise, they dropped sharply when free trade came out but soon after prices are rocketing almost 10m per day. If I were you, I'd hold it till the 100s.
if i were u ,i would keep red mask till it raises to 150-160mil,then sell it...wait till it drops to 120-130mil then rebuy it,then do the same again and again...unless u plan to keep it for collection purpose,then u had no reason not to follow my method*
I have a mask set right now too and I'm not sure what to do with it, they're all rising at the moment and I've seen mask sets go for about 250M+ so I'd say hold onto them.