The pictures are of an FDC and a device next to it that says, “Fire Dept. Indicator Valve.” I’m assuming that there is a valve somewhere. The site glasses have lights (I guess they are lights) indicating whether the valve is open or closed. The site glass on the left has condensate on the inside so it is hard to see in but I imagine it’s just like the right side. There is no valve in close proximity. This device sits about 50′ in front of the building that it belongs to. I saw it in passing and did not have a chance to do a whole lot of digging into exactly what it controlled or was an indicator for. I found it odd that it was right next to the FDC but thinking about it I don’t think it has anything to do with the FDC. If you’ve seen this device or are familiar with it’s function drop in the comments section and share.