A swimming pool chair for use within a pool has a base that interfaces with the floor of the pool. To reduce manufacturing costs andor the installation space required for the electrohydraulic valve control device, at least two synchronously controlled gas-exchange valves are connected using a coupling element to a common valve actuator, and the connection sites of the gas-exchange valves are flexibly formed on the coupling element. Exposed portions of the substrate are etched to provide an unetched raised portion. The contact element has a base part and feet which press-fit into the orifices of the circuit board. The database is then made available via an online data marketplace which allows users from different organizations to buy and sell related data, associated advertisements, and access to the communities of end-users who may also view advertisements and make purchases. A second cavity is formed between the second substrate and the infrared detection unit.