The VISIC100SF by Sick is a tunnel sensor designed for measuring visibility, CO, and NO concentrations. This device is the only available unit that uses scattered light measurement principle having electrochemical cells. Also, the unit is just easy to operate , maintain and mount. Using this, it does not require anymore configuration and alignment enabling it to save time and proceed to the operation immediately. It comes with an enclosure rating of IP6K9K which makes it able to withstand undesirable ambient condition especially inside a tunnel. The device is made with a design which ensures reliable and efficient operation that has long interval maintenance. Plus, the unit has different version that can comply with fog. With these features, it is the best device offering specific solution for different operation.