An apparatus for venting a pressure buildup, the apparatus comprising: a venting member for mounting to an opening of a chamber; a generally flat mounting portion of the venting member for operatively mounting the venting member to the chamber and having a weakened area thereof; a middle portion of the venting member inboard of the flat mounting portion and having a domed portion for extending over and covering the chamber opening with the flat mounting portion operatively mounted to the chamber when a pressure level within the chamber is below a predetermined threshold level and for shifting away from the mounting portion at the weakened area when the pressure level increases beyond the threshold level; and a retainer member mounted to the generally flat mounting portion of the venting member to extend across the weakened area of the venting member flat mounting portion so that the domed portion extends over and covers the chamber opening when the pressure level is below the threshold level and shifts away from the flat mounting portion when the pressure level is above the threshold level to relieve pressure in the chamber, wherein the middle portion includes a generally flat outer portion extending around the domed portion; and the retainer member includes a frame portion and at least one vent retainer portion, the at least one vent retainer portion extending across the flat mounting portion of the venting member, the weakened area, and the middle portion flat outer portion so that the at least one vent retainer portion restricts the middle portion from shifting away from the flat mounting portion when the pressure level is below the threshold level, the apparatus being characterized in that the at least one vent retainer portion extends from the retainer member so that the at least one vent retainer portion bends away from the middle portion to allow the domed portion to shift away relative to the flat mounting portion when the pressure level is above the threshold level. a venting member for mounting to an opening of a chamber; a generally flat mounting portion of the venting member for operatively mounting the venting member to the chamber and having a weakened area thereof; a middle portion of the venting member inboard of the flat mounting portion and having a domed portion for extending over and covering the chamber opening with the flat mounting portion operatively mounted to the chamber when a pressure level within the chamber is below a predetermined threshold level and for shifting away from the mounting portion at the weakened area when the pressure level increases beyond the threshold level; and a retainer member mounted to the generally flat mounting portion of the venting member to extend across the weakened area of the venting member flat mounting portion so that the domed portion extends over and covers the chamber opening when the pressure level is below the threshold level and shifts away from the flat mounting portion when the pressure level is above the threshold level to relieve pressure in the chamber, wherein the middle portion includes a generally flat outer portion extending around the domed portion; and the retainer member includes a frame portion and at least one vent retainer portion, the at least one vent retainer portion extending across the flat mounting portion of the venting member, the weakened area, and the middle portion flat outer portion so that the at least one vent retainer portion restricts the middle portion from shifting away from the flat mounting portion when the pressure level is below the threshold level, the apparatus being characterized in that the at least one vent retainer portion extends from the retainer member so that the at least one vent retainer portion bends away from the middle portion to allow the domed portion to shift away relative to the flat mounting portion when the pressure level is above the threshold level.