The SAI-Ambrosini SS.4 was an Italian fighter

Fighter aircraft

A fighter aircraft is a military aircraft designed primarily for air-to-air combat with other aircraft, as opposed to a bomber, which is designed primarily to attack ground targets...

 prototype developed in the late 1930s but never mass produced. The radical design for its day featured a canard

Canard (aeronautics)

In aeronautics, canard is an airframe configuration of fixed-wing aircraft in which the forward surface is smaller than the rearward, the former being known as the "canard", while the latter is the main wing...

-style wing layout and a 'pusher' propeller

Propeller

A propeller is a type of fan that transmits power by converting rotational motion into thrust. A pressure difference is produced between the forward and rear surfaces of the airfoil-shaped blade, and a fluid is accelerated behind the blade. Propeller dynamics can be modeled by both Bernoulli's...

. Although intended as an air-superiority interceptor

Interceptor aircraft

An interceptor aircraft is a type of fighter aircraft designed specifically to prevent missions of enemy aircraft, particularly bombers and reconnaissance aircraft. Interceptors generally rely on high speed and powerful armament in order to complete their mission as quickly as possible and set up...

, the SS.4 never entered service because the design suffered from numerous faults which caused the prototype to crash-land, killing the test pilot. The design, although unique, barely compared favorably to contemporary fighters, and the Regia Aeronautica decided not to pursue the design because of these shortcomings.
Italian aircraft developed between the World Wars had widely varying characteristics.