De-Icer boots are placed on the leading edge of tails, wings, and propellors, to remove ice during high altitude flight. They typically work by inflating the boot with a pressurized freeze-resistant liquid, so that the ice breaks off.
So far, we have come by three B-17 de-icer boots, and one B-23 boot.
Below, is a B-17 wing boot, unrolled. It was stored in paper packing, which it is laying on.