Venting. The last 3 packs of strings I opened have corrosion ranging from moderate to severe (need a tetanus shot to play them). Two EB Cobalts and one GHS. The cobalts on the wound strings and the GHS on the plains. I whined about this once before here and it seemed like it wasn't all that common. Yes I'm in Florida but I keep my strings in plastic bags and they're usually factory sealed in plastic nowadays anyway. I don't change strings on certain guitars very often, maybe once a year, but what the heck why don't these new strings keep better? I think from now on I'm only going to buy coated strings (DR's or Elixirs) because they don't seem to rust.