The invention includes a method of using a cap containing an internal
thread form matching an external thread form on a flexible throat for a
collapsible tube enclosing at least one contained product. Twisting the
cap engages the internal thread form and the external thread form. These
collectively urge the cap and the flexible throat to seal the contained
product into the collapsible tube. Deforming the flexible throat through
squeezing the collapsible tube dispenses essentially all the product. The
collapsible tube may preferably include an external thread form on a
flexible throat coupled to a flexible shoulder. The external thread form
mates to a cap with an internal thread form urging the flexible throat to
seal against the cap when the cap is twisted onto the flexible throat.
The flexible throat and flexible shoulder flatten to dispense essentially
all of the product.