Control sample of a deep-frozen product or a product, whose keeping temperature must be checked

Check sample for a deep-frozen product or a product, whose keeping temperature has to be checked, comprising:

• a case sealed in an inviolable manner, which is at least partly transparent, which has a predetermined internal shape and which has a meltable object located in said case having a predetermined shape, said object being at least partly different from the internal shape of the case and having a volume smaller than the internal volume of the case, said object having one of a melting point equal to or below the thawing temperature of said product and a melting temperature equal to or below the keeping temperature of said product, the predetermined shape of said object being impossible to be reconstituted following even a partial heating or thawing of the product resulting in partial melting of said object and despite subsequent product refreezing or cooling conditions, wherein said case comprises a first part which is located within the product and is thus invisible and integral with the product and a second visible part integral with the first part,
• said object comprising a first portion filling the first invisible part of the case and a second portion having a shape which is at least partly different from the internal shape of the second visible part of the case, said second part of the case having at least one transparent window for rendering said object visible wherein said object is filled in said first part and extends into said second part.