The Republic of Slovenia will send 28 M-55S main battle tanks to Ukraine. M-55S is a T-55 modernization developed by the STO RAVNE company and engineers of the Israeli company Elbit. Slovenia modernized 30 T-55 tanks in the inventory of its armed forces. The last T-55 was modernized to the M-55S standard in May 1999. In return, Slovenia will obtain from German-made Marder tracked armored infantry fighting vehicles and Fuchs 6×6 armored vehicles, including 35 heavy 8×8 hook loaders and five heavy water tankers, the statement reads. Slovenia also provided 35 BVP M-80A tracked armored infantry fighting vehicles (IFVs) to Ukraine. The ring exchange will also strengthen defense cooperation between Slovenia and Germany.
The T-54/55 is a Soviet medium tank, not even a main battle tank, which weighs only 36 tons. The T-54/T-55 tank series is the most widely used tank in the world and has seen service in over 50 countries. It has also served as the platform for a wide variety of specialty armored vehicles. Overall Slovenian Ground Force T-55s were modernized to the M-55S/M-55S-1 standard. The original 100 mm tank gun was replaced by the NATO-standard 105 mm one with a thermal sleeve. The armour protection of the tank was improved considerably by attaching Rafael ERA blocks to the hull and the turret. This armour is believed to be the latest Israeli Super Blazer system which gives a high level of protection against High Explosive Anti-Tank (HEAT) attack but cannot be activated by small arms fire.
A digital ballistic computer was installed in order to improve the fire control system (FCS). The gunner has the Fotona SGS-55 two-axis stabilized day-and-night sight with an integral laser rangefinder. In addition to the integral optic sight the commander has the Fotona COMTOS-55 sight with an independent line-of-sight stabilization, which allows him to acquire targets and lay the gun independently if required. The driver has the Fotona CODRIS combined day/night observation periscope. The LIRD-1A laser illumination warning receiver was mated with front-mounted IS-6 smoke grenade launchers (of which there are six in two clusters, one per side of the turret) and can be automatically activated in an emergency.
Modernization of the V-12 diesel engine resulted in an increase in power from 520 hp to 600 hp. The engine and crew compartments are each fitted with a fire-detection and suppression system. Each of these systems comprises optical detectors, cylinders filled with Halon 1301 gas and a control device which can be operated automatically or manually. The tank can also lay a smoke screen by injecting diesel fuel into the exhaust outlet on the left hand side of the hull. As an option a new power pack that includes a MAN 850 hp diesel can also be installed. With a combat weight of 40 tonnes, this power pack would give a good power-to-weight ratio of just over 21 hp/tonne. The running gear has rubber side skirts and the tank was outfitted with new rubber and metal tracks.