Abstract: A variable-volume receptacle, especially for use as a compensating receptacle in heating systems. The receptacle includes two membrane-like sheets of rubber or synthetic material; the sheets have the same surface areas, and are placed against one another. The edges of the sheets are bound together by a peripheral U-shaped strip which is attached to both sides. The novel edge connection is considerably more durable than the conventional overlap connection, and as a result of not being susceptible to the otherwise constant danger of tearing due to having been folded, the connection also has a much longer life than do the heretofore known overlap connections.