Deicing boot

The black rubber deicing boot on the wing of a Bombardier Dash 8 Q400 passenger aircraft is inflated with air, producing ridges to crack and dislodge any accumulated ice.
Operation of deicing boots
De-icing rubber boots on the wing leading edge of a Beechcraft 350

A deicing boot is a type of ice protection system installed on aircraft surfaces to permit a mechanical deicing in flight. Such boots are generally installed on the leading edges of wings and control surfaces (e.g. horizontal and vertical stabilizer) as these areas are most likely to accumulate ice which could severely affect the aircraft's performance.