An exhaust gas treatment unit includes a substantially cylindrical exhaust gas treatment body having a main axis and, on at least one opening side of the exhaust gas treatment unit, at least one of the following connecting devices or connectors: an offset compression zone or a molded structure for form-locking engagement. An internal combustion engine includes at least one exhaust gas treatment unit and at least one exhaust gas conducting line. The at least one exhaust gas treatment unit is completely introduced in the at least one exhaust gas conducting line. A motor vehicle having at least one exhaust-gas treatment unit is also provided.