Protective cover or envelope

Claim 1

A PROTECTIVE COVER OF THE CLASS DESCRIBED, COMPRISING A PAIR OF RELATIVELY FLEXIBLE SHEET PLASTIC PANELS OF GENERALLY RECTANGULAR FORM DISPOSED IN OVERLYING RELATION TO EACH OTHER, CERTAIN OF THE MARGINAL EDGES OF THE RESPECTIVE PANELS BEING DISPOSED IN REGISTER AND BONDED TOGETHER, WITH THE EDGES OF THE PANELS AT ONE COMMON END OF THE COVER BEING UNATTACHED AND DEFINING A MOUTH TO PERMIT INSERTION OF ARTICLES INTO AND REMOVAL THEREOF FROM THE COVER SAID MOUTH EXTENDING GENERALLY PERPENDICULAR TO ONE TERMINAL END OF THE BONDED EDGES OF THE PANELS, AND AT LEAST ONE OF THE PANELS HAVING A STRAIN DIVERGING AND DEPLOYING NOTCH PROVIDED IN ITS FREE EDGE AT THE MOUTH AFORESAID ADJACENT TO BUT LATERALLY SPACED FROM THE BONDED PANEL EDGES, SAID NOTCH BEING EXTENDED INWARDLY OF THE MOUTH FROM THE FREE EDGE OF THE LATTER PANEL AND BEING OF SUCH DEPTH AS TO SUBSTANTIALLY REDUCE STRAINS ON THE TERMINAL END OF THE BOND AT THE MOUTH OF THE COVER WHEN THE PROTECTIVE COVER IS IN USE, THE EDGES OF THE RESPECTIVE PANELS BEING REGISTERED ALONG THREE SIDES AND BEING BONDED ALONG A CONTINUOUS LINE OF SUBSTANTIALLY UNIFORM WIDTH EXCEPT AT ITS EXTREME ENDS, SAID BOND LINE TERMINATING AT THE OPPOSITE CORNERS OF THE FOURTH SIDE TO DEFINE AN ENVELOPE WHICH IS OPEN ALONG THE LATTER SIDE WITH A CORRESPONDING NOTCH BEING PROVIDED IN AT LEAST ONE PANEL ADJACENT TO EACH TERMINAL END OF THE BOND LINE, AND EACH TERMINAL END OF THE BOND LINE BEING LATERALLY ENLARGED IN THE ZONE OF THE ENVELOPE MOUTH.