service, in September 1938, but irregularities and disputes over payment delayed the transfer of the production drawings until October 1939. His factory built one prototype, mostly from R-1 spare parts, but never began production. Sweden: Strv m/37 (AH-IV-Sv) Sweden ordered forty-eight tankettes in 1937 as the Stridsvagn m/37 (Strv m/37) after a successful demonstration during winter conditions in the Krkonoše Mountains. They were to be assembled in Oskarshamn with a more powerful , water-cooled, six-cylinder, Volvo FC-CKD gasoline engine and armor, up to thick, from Avesta, although ČKD supplied most of the other components after building one prototype. The vehicle was heavily modified with the driver's machine gun deleted and proved to be the heaviest and largest version of the AH-IV at and a length of , a width of and high. Its turret mounted two Swedish Ksp m/36 strv machine guns and sported a small observation cupola on its top. It carried a radio and 3960 rounds for its machine guns. It had a maximum speed of and a range of . It could ford a stream up to in depth. The last components were shipped in November 1938. Ethiopia: AH-IV-Hb Ethiopia ordered twenty AH-IV-Hb tankettes on 24 June 1948. In form these reverted to the driver's machine gun and single machine gun in the turret, but were of welded construction rather than riveted. They used a , air-cooled Tatra 114 diesel engine that produced at 2200 rpm. This gave the AH-IV-Hb a top speed of and a range of . It weighed and had a length of , a width of and was high. It had a ground pressure of only 0.48 kg/cm2, could ford a stream up to in depth, but could only overcome an obstacle high. It used the ZB vz. 26 and vz. 37 machine guns, for which it carried 2800 rounds. Operational history Iran The AH-IVs were split between the 1st and 2nd Infantry Divisions in service. Nothing more is known of their service or when they were withdrawn. Romania The R-1s were assigned to the cavalry brigades, two platoons of two or three tankettes apiece. All eighteen belonging to the Cavalry Corps were grouped into the ad hoc "Korne Mechanized Detachment" during the opening stages of Operation Barbarossa, but all were out of commission by 1 October. Twenty-nine of the original thirty-five were allocated to the six cavalry divisions (redesignated from brigades on