The sensor measures a small 26 mm wide x 64 mm long x 5 mm thick (1.04 x 2.5 x 0.2 in) which makes it very easy to mount. Detector cells are totally sealed, are never in contact with the water, will not corrode and are not affected by oil or foreign debris. Features No moving partsTotally sealed solid state electronics and field detectorsNo mercuryNo exposed sensors eliminate corrosion possibilitiesUnique 3-way switch disables piezo alarm while keeping warning LED litEnvironmentally sensitiveMeets ISO 8846The Bilge Alert sensor should be mounted on the bulkhead, stringer, inner transom or hull of your boat above the normal operating level of your automatic float switch, but below the level of critical components of your boat and/or engine; such as the starter. If water disrupts the sensor for more than 8 seconds the alarm and warning LED will be triggered. Field effect dector cellsMirus dector cells are composed of an active device and an electrode surrounded by a second electrode. The applied circuit creates an electric field around the cell. When a dielectric material (such as bilge water) interrupts the field the active device responds by outputting a signal. In the case of the Bilge Alert, this signal is used to sound a loud (100db) alarm and light a warning lamp on the control panel.Technical DataWidth: Detector 26 mm - 1.04", Alarm 63 mm - 2.47"Height: Detector 5 mm - 0.2", Alarm 50 mm - 1.97"Length: Dectector 64 mm - 2 Wire size 16 Ga. Tin coatedHousing ABS ThermoplasticWire length 762 mm - 30" Passive amp 16 mA Max amp 20A, 12 V