pressure equalizer 4900 is provided with one or more features on its outer surface it is advantageous to pinch the pressure equalizer 4900 and then insert the pressure equalizer 4900 into the container 49 once inserted the pressure equalizer 4900 can be released thereby allowing the pressure equalizer 4900 to return to its initial geometry and recess itself into the depressions features within the inside of the container 49 in some embodiments it may be desirable to provide a pressure equalizer 4900 that is constructed of a material that is capable of deforming elastically under compression or tension such that its largest external feature can fit within the smallest internal feature of the container 39 s 49 bottleneck more specifically the pressure equalizer 4900 may be at least partially constructed of a polymer such as plastic rubber and the like even more specifically the pressure equalizer 4900 may be constructed of any recyclable material and the type of material selected for manufacturing the pressure equalizer 4900 may be based on the material s used to construct the container bottle in some embodiments the material used for the pressure equalizer 4900 may correspond to the same material used to make the container 49 more specific examples of materials that may.