A clip arrangement is described for releasably fastening an object to at least one line with a clamping part which can be snapped onto the line and a retaining part to releasably fasten the object between the retaining part and clamping part. A self-sealing microwave package includes a sheet of insulating material including a first surface, and a thermally activatable adhesive applied to at least a portion of the first surface. In one embodiment, power supply circuitry in the unit includes one or more solar power cells that convert solar energy into electricity to power both the unit and the field device.