The Hydros Reed Switch is a versatile control component designed to integrate into your saltwater aquarium system. It allows you to add a sensor near cabinet doors or other areas where it can detect the presence of a magnet, triggering an event such as sounding an alarm or illuminating lights when the door opens. The reed switch has a sensing distance range of 10mm-15mm and is compact at just 2915.59mm in size. It supports continuous operations with up to one million switching cycles, making it reliable for long-term use. To utilize this product effectively, you will need the HYDROS Control device with a free channel and the corresponding Hydros 0-10V Quad Cable.