VESSEL WITH AT LEAST ONE OBSERVATION DOOR, PARTICULARLY TAPE CASSETTE AND OBSERVATION DOOR

PURPOSE: To make the contact part between a case and a window inconspicuous visually by hiding a fixing parts offending the eye between both parts, especially, points of weldings and points of fusion weldings in a case having a window and in a viewing window for an opaque or transparent case of the part of the case. CONSTITUTION: Concerning a case, especially a tape cassette is provided with at least a window part 7 capable of being fixed to the cut part of a cabinet 6 at fixing part and constituted of a window part having parts whose transparency properties and different. The case or the cassette has such features, that parts, whose transparency properties are different, are constituted of a transparent, part 9 and a hiding part 10, and the part 10 hides at least the upper side of fixing parts.