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 {TAIL ~ the exterior} of the second compartment 42 
is applied to
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 { TAIL ~ the exterior } of 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 REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH