A very common pack mostly used for the goods display, the blister is a combination of a transparent plastic cavity with a backing paperboard normally used for product informations, instructions for use and for advertising. There are different ways to seal or close the blister and the paperboard: Blister thermowelded to a paperboard pretreated with a special glue. Such blisters generally have a slot on the top, well balanced in the middle to hang the product perfectly. Blisters closed by high frequency welding generally have two cavities; during the packaging is possible to palce a piece of paperboard with advertising or, if necessary, an instruction booklet. This type of blister is ideal for large retailers because of the wide and clear display and safe thanks to a strictly closing that avoid the product removal. Sliding Blisters, differents one from another because the paperboard slides into two or three folds on the back allowing the product to be packaged manually. This solution is suitable for retail because the package can be opened to show the product and then closed without damage or breaks.