Increases the sensitivity of the combustible (LEL) sensor and provides audible/visual pulses that speed up as you get closer to a leak source. Bar Hole Mode:
If you are referring to "RKI 057" in a different context—such as a specific part number, a flight identifier, or a chemical compound—please provide additional details so I can refine this information for you. Rki 057
Below is a deep write-up covering both likely interpretations. Increases the sensitivity of the combustible (LEL) sensor