This weapon was designed by Ion Mihaita in 1989 for use by military and police forces in close combat, particularly in urban combat. The weapon has a secondary use as a longer-ranged weapon for precise shots. The weapon has two barrels, two receivers, and two magazine inserts to feed what are essentially two weapons melded into one. The user may fire one or both barrels, with both on automatic, both on semi automatic, or one on automatic and one on semi. Two selector levers are provided to enable this. The front magazine feeds the lower barrel, and the rear magazine feeds the upper barrel.
IM-Arms Model 1 or ITM-1: The first prototype had both barrels 9x19mm but used different magazines.
IM-Arms Model 2 or ITM-2: An improvement of the Model 1, but came with shorter heavier barrels, stronger internal components, and a higher rate of fire as well as fed from the same magazines.
IM-Arms Model 3 or ITM-3: A combined battle rifle/SMG: the lower barrel was in 9x19mm fed from UZI mags, the upper one was in 7.62x51mm fed from AK mags. Although double barreled, it must be noted that the Model 3 is a different weapon than the submachine guns.
IM-Arms Model 4 or ITM-4: The final improvement of the Model 2, but fed from UZI mags.
As for the ITM twin-barrelled weapons made by IM-Arms, it was a full line of over-and-under weapons with two barrels, two feeding systems, but only one trigger. The barrel the operator fired was chosen by selector, or could fire both together. Usually the top barrel was used for long range shots, and a shorter lower barrel for the close range work. In one case, you had two different calibers. ITM firearms were way too odd to be considered by any professional operator and were also so complicated that any serious operational use could result heavily compromised by any eventual damage that would have called the operator to field strip the weapon and try to maintain.