This is an injection-plastic aircraft model kit.
From the manufacturer:
Develiped from earlier Bf109E variants, the Bf109-4/N Trop was modified for use in the arid and dusty conditions of the North African desert. The large tropical filter covering the engine's air intake being the most obvious difference between this and the standard E-4. Upon introduction to the desert war the tropical Bf109s were more than a match for the RAF's Hurricanes and Tomahawks and it was not until the introuction of the Spitfire Mk.V that the balance was redressed.