A device for packaging a product which can be included with an article, such as an article containing a first cosmetic product. The device includes a sachet containing a second product, in particular a sample cosmetic product, which may be the same as the first or different. In addition, a sheet is folded so as to delimit a compartment in which the sachet is accommodated, with the sheet including information relating to at least one of the first and second products. A packing assembly is also provided, which includes a package having a container therein for a first cosmetic product, with the folded sheet accommodating the sachet of a second cosmetic product also positioned in the package.