SCP-1499 is a Soviet GP-5 gas mask. The anomalous effects of SCP-1499 activate when a human places SCP-1499 on their head. Approximately one second after SCP-1499 is fully secured on the subject's head, the subject vanishes from view, and is no longer detectable. When worn, the person is transported into a dimension containing many entities designated SCP-1499-1.