A rupture disk is provided for relieving pressure between the interior and exterior of a battery box, the box having an outlet opening. The apparatus includes a first layer that provides a gasket which abuts the battery box, the gasket having a central opening which aligns with the battery box opening. A second layer is in the form of a reverse buckling disk having a disk flange, a domed portion and a weakened portion on the dome that defines a disk burst pressure, the second layer having concave and convex sides. A third layer is an outlet ring that sandwiches the second layer in between the first and the third layers, the outlet ring having a central opening surrounded by an edge. A plurality of teeth on the third layer extend from said edge inwardly a distance. A plurality of tabs are provided on the first and third layers.