A Simple Way to Organize and Mount Probes The IceCap magnetic probe holder universally mounts tubing securely to most smooth locations up to 1/2in thick. Magnetic holder can be fixed on the sump or aquarium wall and can hold up to 4 Probes. Dimensions (LxWxH): 3.5 x 2 x 1.75in. Package includes wet side with 4 probe ports, 4 nylon screws and dry side magnet. Body color is white, screws are black.