referring to fig1 to 9 of the drawings , the wraparound enclosure is designated generally by the reference numeral 20 while the container for a tape cassette is designated generally by the reference numeral 21 . the container 21 forms no part of the present invention and will be recognized as a conventional package for a cassette containing magnetic tape . the wraparound enclosure 20 of the present invention has a first section 22 interconnected with a second section 23 for installation about the container 21 . a surveillance tag 24 containing electronic components detectable by a microwave surveillance unit is secured adhesively within a recess in the back wall 25 of the section 22 . the wall 25 cooperates with side walls 26 and 27 at the right and left sides and a side wall 28 at the front , all of which extend normal to a primary wall 29 , and with the primary wall 29 , to form a receptacle or first section of an envelope for receiving the container 21 . a plurality of vertical ribs 30 , 31 , 32 and 33 are located , buttress like , at the general locations seen in fig2 both for centering the container 21 within the first section and for a purpose to be described below . the second section 23 of the enclosure is similarly provided with side walls 34 , 35 and 36 cooperating with a primary wall 37 . however , although the first section 22 has side walls along all four side edges of its primary wall 29 , the second section has side walls along only three of its four side edges , it having no side wall along the back edge of its primary wall 37 . as shown in the drawings , the enclosure , preferably formed from clear plastic material , has its first and second sections , 22 and 23 , joined along a back edge by a strap member 38 joined to each of sections 22 and 23 by a living hinge 39 and 40 , respectively . the primary wall 29 of section 22 is provided with a central rectangular opening 41 while primary wall 37 of section 23 is provided with a similar rectangular opening 42 . the openings 41 and 42 are provided both for the purpose of enhancing visual impact of the contents of the wraparound enclosure and facilitating interaction with the releasing mechanism in a manner to be described hereinafter . the first section 22 of the envelope has its side walls provided with a plurality of latches 43 to 48 projecting therefrom , two from each of side walls 26 , 27 and 28 . the second section 23 has its side walls 34 , 35 and 36 provided with the strikes 49 to 54 with which the respective latches 43 to 48 mate when the enclosure is placed in its closed condition wrapped around the container 21 . the side walls 26 and 27 of the first section 22 , at the right and left sides thereof , near the back edge , are formed with respective notches 55 and 56 extending inwardly from the free edge of the side wall toward the associated primary wall 29 . the mating side walls 34 and 36 of the second section 23 are provided with t - shape lugs 57 and 58 , respectively , for interengagement with the corresponding notch 55 and 56 , respectively , for a purpose to be described . as best seen in fig5 and 9 , the side wall 25 of section 22 adjacent the back edge thereof is located inward adjacent the living hinge 39 such that upon closure of the sections 22 and 23 the strap member 38 overlies the side wall 25 with a close fit . the primary wall 29 of section 22 projects beyond its respective side walls along its right , left and front edges over a major portion of said edges presenting the flange portions designated by the numeral 59 . when the enclosure is in closed condition the flanges 59 tend to bar access to the interface region between overlapping side walls of the first and second sections . it may be observed that the ribs 30 , 31 , 32 and 33 are located at points along the respective side walls intermediate the locations of the latches on such side wall . referring , for example , to latches 43 and 44 on side wall 26 , if the latch 44 , for example , were deflected inwardly toward the opposite side wall 27 , the buttress support afforded by rib 30 will oppose communication of such inward displacement of the wall 26 , that occurs adjacent latch 44 , to the adjacent latch 43 . in similar manner , ribs 31 and 32 isolate latch 47 from latch 48 while rib 33 isolates latch 45 from latch 46 . as best seen in fig2 the inner surfaces of the side walls of section 23 are provided with grooves or channels 60 to 65 associated respectively with strikes 49 to 54 . the grooves or channels 60 to 65 provide guideways and reliefs for facilitating entry of the corresponding latches 43 to 48 into engagement with the corresponding strike . as shown , the grooves stop short of the strike area . on the external surface of the side walls the area around each strike is reinforced by a u - shape ribbed protuberance 66 to 71 , respectively . besides reinforcing the side wall the protuberances 70 and 71 perform an additional function with respect to the releasing mechanism that will be described hereinafter . in addition , the protuberances provide an additional guard resisting tampering by devices other than the special releasing mechanism for opening the enclosure . when a cassette in its container 21 is disposed within section 22 of the enclosure , the latter may be closed by folding one section over the other . the section 22 telescopes within section 23 while the t - shape lugs 57 and 58 enter the respective notches 55 and 56 in the manner illustrated in fig7 . a chamfer on each of the latches 43 , 44 , 45 and 44 , as shown at 72 in fig6 functions as a camming surface to facilitate the passage thereby of the side walls 34 and 36 of section 23 . upon bringing the two sections of the enclosure together , all of the latches 43 to 48 engage their respective strikes as best seen in fig8 . as seen in fig9 the t - shape lugs 57 and 59 cooperate with the mating notches 55 and 56 to prevent separation of the respective overlapping right and left side side walls 26 and 34 on the one hand and 27 and 36 on the other hand in a direction normal to such side walls ; that is , the interengaging means prevents the side walls from being pried apart from the hinge end of the enclosure . referring now to fig1 to 17 , there is shown therein the releasing mechanism for unlatching and opening the wraparound enclosure 20 , the releasing mechanism being designated generally by the reference numeral 101 . the releasing mechanism has a housing 102 fastened to a base plate 103 on which is mounted the various components for supporting the enclosure 20 and releasing the latches while applying opening force thereto . support for the enclosure 20 is provided by a frame assembly 104 having horizontally disposed flanges 105 and 106 which engage the undersurface of the enclosure 20 when it is fully inserted . a z - shape member 107 formed from spring sheet metal is fastened to the base plate 103 by an integral tab 108 . the member 107 has a generally vertical rear portion 109 terminating in a curled lip 110 , an inclined intermediate portion 111 , and a forward dependent portion 112 terminating in a narrow tab 113 which is engaged by and centers a coiled compression spring 114 supported by the base plate 103 . as best seen in fig1 , the article 20 is inserted with the wall 29 uppermost and in the direction indicated by the &# 34 ; arrow &# 34 ; 72 ( see fig1 ) such that its rear side wall , now the strap member 38 , is engaged against the portion 109 of the member 107 under the lip 110 while the knee 115 formed between the portions 111 and 112 of the element 107 bears against the cassette container 21 through the opening 42 in the enclosure 20 . as the enclosure 20 is urged downwardly and rearwardly relative to the releasing mechanism , the spring members 107 and 114 are loaded , i . e ., member 109 is deflected rearwardly , portions 111 and 112 are deflected downwardly while helical spring 114 is placed under compression . insertion of enclosure 20 continues until the front protuberances 70 and 71 penetrate the apertures 116 and 117 , respectively , in the front plate 118 which forms a part of the frame assembly 104 . the interengagement between the apertures 116 and 117 , on the one hand , and ribbed protuberances 70 and 71 , on the other hand , in cooperation with the lip 110 , serves to grasp and secure the section 23 of the enclosure 20 in the position shown in fig1 and 15 . for releasing the latches on the enclosure 20 , there is provided a u - shape lever 119 having side arms 120 and 121 joined by a cross member 122 . the lever 119 is mounted by its arms 120 and 121 on the opposite ends of a hinge pin 123 which is , in turn , carried by the frame 104 . spacers 124 and 125 separate the arms 120 and 121 , respectively , from the sides of the frame member 104 . tension springs 144 between base plate 103 and the respective ends of lever arms 120 and 121 bias the lever 119 in a counterclockwise direction as seen in fig1 . rocker plates 126 and 127 , biased by respective tension springs 128 and 129 , are pivotally supported at their lower edges 130 and 131 in the base plate 103 . the upper edges of the plates 126 and 127 are provided with latch engaging fingers 132 which pass through the apertures 133 in the frame assembly 104 for engaging the individual latches 43 , 44 on one side , and 45 and 46 on the other side of the enclosure 20 . in similar manner , for engaging the forward latches 47 and 48 of the enclosure 20 , there is provided a rocker plate 134 spring biased by tension spring 135 and pivotally mounted at its lower end 136 in the base plate 103 . the upper end of the plate 134 is provided with the fingers 137 which pass through the apertures 116 and 117 to engage latches 47 and 48 . actuation of the rocker plates 126 and 127 is accomplished by respective cam fingers 138 and 139 struck from the respective arms 120 and 121 of the lever 119 . thus , as illustrated in fig1 , the finger 138 bears against and displaces the plate 126 as the lever 119 is depressed through pressure upon its cross member 122 . similarly , the finger 139 engages and displaces the plate 127 . a knee action plate 140 is pivotally secured to the lever 119 at 141 and pivotally interconnected at its opposite end with the plate 134 by fingers 142 passing through apertures 143 . as best seen in fig1 , as the lever 119 is depressed , the knee action member 140 displaces the rocker plate 134 to the left so as to urge the fingers 137 into unlatching engagement with the latches 47 and 48 . it should now be understood that as soon as lever 119 has been depressed sufficiently to urge all of the rocker plates 126 , 127 and 134 into unlatching position as seen in fig1 , 16 and 17 , the spring pressure developed by members 107 and 114 will elevate both the cassette container 21 and the section 22 of enclosure 20 to the position shown generally in fig1 . the section 22 can then be opened further manually , the cassette container 21 removed , and the entire enclosure 20 thereupon extracted by lifting vertically from the releasing mechanism 101 . having described the presently preferred embodiments of the invention , it should be understood that various changes in detail of construction may be made by those skilled in the art without departing from the true spirit of the invention as defined in the appended claims .