The operation of BASI’s level probe BLCSO is based on the changing of light reflection when liquid covers an optical sensor, mounted on the top of the probe. This model can be used as a single level switch for sensing presence or absence of liquid. It is applicable for the most of the low-viscose industrial liquids as well as the liquids in food industry, thanks to its stainless steel casing and polysulphone light sensor. The BLCSO switch can be equipped with either transistor output, or contact relay output, and the power supply voltage can vary from 12 to 24 VAC/DC, providing convenient application. Two variants are available according to the electrical connection: connector-type (for side mounting) and cable-type (for side mounting and submersible usage). Thanks to its operating principle, power output, and low price, BLCSO can be very useful in applications where float and conductive sensors are not applicable and capacitive or pressure sensors are too expensive.