The details of the valve shown are more fully illustrated in
FIGS. 4 and 5 wherein the flaplike member 21 is generally thin
in cross section and is generally circular in shape to conform
to the interior cross section of the tube. and has an upstanding
tab portion or small projection 26 along its upper edge which
extends through a narrow slot 27 in the top of the tube and
curls over back against itself to form a head 28 outside the
tube so as to hingedly support the flaplike member 21 for
pivotal movement in the tube.