The bin sensor uses a pair of garage door safety sensors that are located on top of the cyclone dust bin and sense any blockage through the flexible duct connection at the bin cover. A special circuit waits for a 15-20 second blockage and triggers a bright strobe light (and switchable horn). The user can easily interface the control unit with the cyclone's power relay for automatic shutdown when the alarm is triggered (I provide guidance for doing it) and a switch is included to allow the user to bypass the automated shutdown when the dust collector needs to stay running such as while planing a long board. The entire unit runs on a small 12 Volt DC power supply and everything is included for easy user setup (over 100 units have been installed in the past two years).
I've attached 2 pictures that show the kit contents and key features of the Control Box: (1) On/Off power switch with LED in the On position; (2) Horn on/off push button switch; (3) Cyclone interconnection bushing (user provides 14/2 NM cable); (4) Normal/Bypass Switch; and (5) the Strobe/Horn unit. The power supply plugs into a jack and the sensors connect to a pair of binder posts both on the left side of the unit as seen in the first picture. The 3rd picture shows a typical installation of the sensors above a dust collection bin on a ClearVue Cyclone. Units have also been installed on several Oneida cyclones as well.
Hope this answers your question!