A sturdy black key is a no-rent key which opens a small, solidly-built safe. It may be Held. The aforementioned safe can be found at Jerad, Paishain, and the Tear brigand leader and is the potential reward for completing chain quests associated with each smob. While the key could potentially be shared between each chain, specific mobol associated items must also be acquired in each chain to open the safe, preventing player abuse.