The FCM F1 was a French super-heavy tank developed during the late Interbellum by the "Forges et Chantiers de la Méditerranée" company.
 Twelve were ordered in 1940 to replace the Char 2C, but France was defeated before construction could begin, a wooden mock-up being all that was finished.
 The FCM F1 was large and elongated, and had two turrets: one in front and one in the back, with a single high-velocity gun in each turret.
 The rear turret was higher so it could shoot over the first one.
 The vehicle was intended to be heavily armoured.
 Its size and protection level made it by 1940, at about 140 tons the heaviest tank ever to have actually been ordered for production.
 Despite two engines its speed would have been low.
 The primary purpose of the tank was to breach German fortification lines, not to fight enemy tanks.
 The development path of the FCM F1 was extremely complex, due to the existence of a number of parallel super-heavy tank projects with overlapping design goals, the specifications of which were regularly changed.
 For each project in turn several companies submitted one or more competing proposals.
The Gundlach Periscope, usually known under its British designation as Vickers Tank Periscope MK.IV, was a revolutionary invention by Polish engineer Rudolf Gundlach, manufactured for Polish 7TP tanks since end of 1935 and patented in 1936 as "Gundlach Peryskop obrotowy".
 It was the first device to allow the tank commander to have a 360-degree view from his turret with a single periscope.
 By rotating the periscope and allowing the tank commander to look backwards through the second eyepiece, he no longer had to change position to look behind the turret.
 Early tanks had small turrets and fixed seating, without an independently rotating cupola, and so the commander wasn't easily able to move himself to another rear-facing periscope.
Flakpanzer IV is the general designation for a series of self-propelled anti-aircraft guns based on the Panzerkampfwagen IV chassis.
 They are, in order of development:
This is a list of Panzerkampfwagen IV variants, including prototypes, conversions and projected designs.
As the American army did not have tanks of its own, the French two-man Renault FT Light Tank was used by US in the later stages of World War I.
 It was cheap and well-suited for mass production, and in addition to its traversable turret another innovative feature of the FT was its engine located at the rear.
 This pattern, with the gun located in a mounted turret and rear engine, became the standard for most succeeding tanks across the world even to this day.
The "Panzerkampfwagen" IV (PzKpfw IV), commonly known as the Panzer IV, was a German medium tank developed in the late 1930s and used extensively during the Second World War.
 Its ordnance inventory designation was Sd.Kfz.
 161.
The idea of superfiring armament is to locate two (or more) turrets in a line, one behind the other, but with the second turret located above ("super") the one in front so that the second turret could fire over the first.
 This configuration meant that both forward or aft turrets could fire at any target within their sector, even when the target was in the same vertical plane as the turrets.
An oscillating turret is a form of turret for armoured fighting vehicles, both tanks and armoured cars.
 The turret is unusual in being made of two hinged parts.
 Elevation of the gun relies on the upper part of the turret moving relative to the lower part.
The 14"/50 caliber gun was a naval gun mounted on "New Mexico" and "Tennessee"-class battleship s.
 These ships also featured the first "three-gun" turrets, meaning that each gun in each turret could be "individually sleeved" to elevate separately (however, they could be linked so they would elevate as a unit, similar to the triple turrets on other Navy ships).
 The 14"/50 caliber guns were designated as Mark 4 and 6, with later versions known as Mark 7, 11, and B.
 These guns were more powerful than the main gun mounted on the previous three classes of US battleships (the "New York" , "Nevada" and "Pennsylvania" class es), the 14"/45 caliber gun.
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The Schmalturm turret was a tank turret designed for use on the Panzer V Ausf.
 B Panther II medium tank, Panther A and G medium tank, Panzer IV Ausf.
 J medium tank and the VK 30.02 DB (a medium tank prototype).
 The turret's shape resembled the Soviet T-34 tank turret.
 It featured a narrow front to maximize protection while minimizing weight.
 It was both lighter and easier-to-manufacture than the standard Panther turret.
 The turret had a stereoscopic rangefinder with lenses on either side of the turret, located in spherical bulges.
 No Schmalturms entered series production.

Question: The schmaltrum turret could be found on what tanks other than the Panzerkampfwagen IV?
Answer: B Panther II medium tank, Panther A and G medium tank