and 20 that is when the side flaps 18 and 20 are folded along their fold lines 22 and 24 to lie over the front panel 12 the adhesive 32 and 34 will be present so that when the back panel 14 is folded along the bottom fold line 16 over the front panel 12 the back panel 14 will be secured by the adhesive 32 and 34 to the side flaps 18 and 20 thus completing the envelope and providing an inner pocket for receipt of desired materials the closing flap 26 also has a layer of adhesive 36 which is typically remoistenable adhesive so that the user may apply liquid to the adhesive 36 and secure the closure flap 26 to the outside of the back panel 14 typically the adhesive layers 32 and 34 are hot melt adhesive applied during the manufacturing process in a high speed production apparatus as above pointed out if the adhesive layers or gum lines 32 and 34 are not properly applied the envelope may not function as designed as a result the measuring gauge of the present intention is utilized to be capable of quickly and easily measuring various portions of the envelope in its completed form to determine whether or not the envelope meets the desired specifications such a measuring gauge 40 is shown in fig2 the measuring gauge 40 is manufactured from a thin transparent material typically plastic such as mylar having a thickness of approximately 0 0010 inches and is constructed in the form of an u201c l u201d shaped device measuring gauge 40 has a first elongated leg or arm 42 which provides the long side or leg of the l and second shorter arm or leg 43 which is disposed.