This is an excellent reproduction (non-airworthy) example of one of the B17's hardest to find parts; for display only. It was in the lower section of the Engine Start panel, to the right of the main instrument panel. It was called the LaFrance CO2 Engine Fire Control Panel. If a fire were to break out in any engine, the co-pilot would turn the center knob to that engine and then pull the handle on that side. With the cowl flaps closed, the engine compartment would be flooded with Carbon Dioxide (CO2) and hopefully the fire would be put out.
The back plate was scanned in high resolution, and some excellent labels were professionally printed from the scan. These were attached to a laser cut 1/16" aluminum plate, which forms the mounting surface for the knobs. Made in the USA.