Abstract: Apparatus, consisting of a single insulated container, configured to contain a cryogen. The apparatus also has a first pump and a second pump, both disposed in the single insulated container and configured to pump the cryogen from the single insulated container while immersed in the cryogen. A first probe and a second probe, having respective first and second proximal ends, are coupled to receive concurrently the cryogen pumped by the first pump and the second pump, respectively. The probes have respective first and second distal ends, which are chilled by the cryogen received through the first and second proximal ends and which are configured to be inserted into a body of a living subject.