As shown in FIG 4, a weakened portion 45 is preferably formed in the middle of the internal seal 43 to cause the seal to rupture when {HEAD ~ pressure} is applied to the exterior of {TAIL ~ the second compartment} 42 
As shown in FIG 4 , a weakened portion 45 is preferably formed in the middle of the internal seal 43 to cause the seal to rupture when { HEAD ~ pressure } is applied to the exterior of { TAIL ~ the second compartment } 42
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH