It is often desirable to mount point-of-purchase display devices on the modular shelving that is used in retail stores. The commonest types of such shelving have hollow steel upright supporting posts at each end of each module, and each supporting post has a line of spaced longitudinal slots in which mounting hooks for the merchandise supporting shelves are engaged. In most cases, the posts of laterally adjacent modules abut one another; although there are certain types of shelving in which a single post supports two adjacent modules.
Various manufacturers of modular shelving use supporting posts of different cross sectional configurations and areas, and the slots in the posts of different manufacturers' shelving are of different lengths and different spacings. Apparatus for mounting point-of-purchase display devices on such modular shelving must be capable of being mounted on the supporting posts of any of the several types of shelving used in retail stores, in order that the company placing the display devices need not have different mounting brackets for each different kind of shelving.
There is one company which markets a "universal" mounting key which is sufficiently universal that only two types of such mounting keys are required to fit many of the slotted hollow steel posts now on the market. Each mounting key is fabricated from a piece of 3/32" (2.38 mm) sheet metal which may be inserted edgewise through a post slot. The key includes a shank which is threaded top and bottom to receive a wing nut, and at one end of the shank are ears which engage the interior of a post above and below a post slot through which the key is inserted. The wing nut may be screwed into firm clamping engagement with the post wall, or with a bracket which is supported upon the shank and clamped against the post wall by the wing nut.
The above-described mounting keys have proved to be satisfactory for connecting supporting brackets to the upright hollow posts of retail shelving. However, the wing nuts which are used on such mounting keys must be of fairly large diameter to function properly, and the span across the wings must be large enough that two such keys may not be used in coplanar slots of the laterally abutting posts of two adjacent modules because the wind nuts interfere with one another; nor, of course, may they be used in a single slot of a post that supports two modules.
There are certain situations in which it is desirable to have several point-of-purchase display devices placed end-to-end above adjacent modules, and there is no way that the above-described mounting keys can be used for this purpose.