A capsule includes a casing having an axis of extension, the casing including a base wall and a lateral wall defining a cavity for containing an initial product. A closing element is fixed to the base wall for perforation by a blade of a fluid injection device The base wall includes an annular edge region extending to the lateral wall, a central region, and a groove, interposed between the central and edge regions, and shaped to receive the blades. The closing element has a central portion fixed to the central region and an edge portion fixed to the edge region. The central region and the edge region extend on respective planes which are offset from each other along the axis such that an intermediate portion of the closing element, interposed between the central portion and the edge portion for closing the groove, is inclined.