1.  Field of the Invention
The present invention generally relates to cover means and more particularly to an improved pop-top can lid which is easy to make, stack and open. 
2.  Prior Art
So-called pop-top can lids are used very extensively on beverage containers for soft drinks, beer and the like.  Each can generally includes a generally circular (in plan view) metal top cover plate, to the upper surface of which is secured a lift tab, one end of which is positioned over a scored area in the plate.  When the tab is lifted at one end, the opposite end positioned over the scored area is rotated downwardly to break the scoring and open the lid for easy removal of fluid from the can to which the lid is attached. 
Unfortunately, each such conventional lid has the same major problem.  Thus, the lift tab is flat and tight against the upper surface of the lid.  Moreover, it is held thereagainst with considerable force to prevent the tab from rattling on the lid.  A fingernail must be forced between the lift tab and lid and then the lift tab must be pried up by the fingernail before it can be moved up above the lid surface sufficiently far to enable the fingers of the hand to grasp it and raise it further.  This prying up is resisted because the drive end of the tab immediately engages the can lid in the scored area as the prying takes place.  Considerable force must be exerted by the fingernail in order to pry the tab up far enough to enable the fingers to take over the task while the scoring is being broken.  During such initial prying it is quite common for the fingernail to break.  This is particularly distressing in the case of girls and women with manicured natural and artificial fingernails. 
Accordingly, such devices as fork tines, knife blades, screw drivers, nail files and the like are frequently used to carry out the initial prying operation.  Certain tools also have been fabricated and sold which slip over the tabs and help the prying operation.  But there are many occasions when external aids such as those mentioned above are not available, and the prying and lid opening must therefore be done solely with the fingernails and fingers. 
Therefore, it would be desirable to be able to provide an improved, easier opening pop-top can lid which would not require the use of the fingernails or external tools to initially pry up the lift tab on the lid.  The can lid should be inexpensive to make and efficient to use.  Moreover, a plurality of the lids should be easily stackable on each other for compact shipment and for the compatability with the lidding machinery before and during assembly with the container can bodies.