a new thermal jacket on the gun barrel to control heating. A less important change was to use rectangular rubber blocks fastened to the treads with a single pin instead of the earlier two-pin "shaped" versions. The rubber blocks could be easily replaced with metal X-shaped crampons for movement on ice and snow in the winter. Between 1974 and 1977 all of the machines in the first four batches were brought to the same Leopard 1A1A1 standard, and given additional turret armor developed by Blohm & Voss. The PZB 200 image intensification system was mounted in a large box on the upper right of the gun, creating the Leopard 1A1A2. A further upgrade with SEM80/90 all-digital radios created the Leopard 1A1A3. In mid-1976 a prototype called Leopard 2AV (Austere Version) because it had a simplified fire control system, was assembled and shipped to the USA. It arrived in the US by the end of August 1976, and comparative tests between the Leopard 2 and the XM1 (the prototype name for the M1 Abrams) prototypes were held from 1 September at Aberdeen Proving Ground, lasting until December 1976. The US Army reported that the Leopard 2 and the XM1 were comparable in firepower and mobility, but the XM1 was superior in armour protection. (Today we know this was true as regards a hit by a hollow charge; but against KE-attack the Leopard 2 was almost twice as well protected as the original M1.) In September 1977 1800 Leopard 2 were ordered, and the first batch of five was delivered on 25 October 1979. The Leopard 2 was made in many variations and became very popular for export in the nineties, when the shrinking German army offered many of its redundant Leopard 2s at a reduced price. It became successful enough in Europe that the manufacturer started calling it the Euro Leopard, but with further non-European orders, the name "Global-LEOPARD" is now used instead. However, France, Britain, and Italy all have their own MBTs currently (Leclerc, Challenger 2 and Ariete respectively). Post Cold War In 1984 Germany planned to develop a new MBT called Panzerkampfwagen 2000 (PzKW 2000). In 1988 the requirements for this tank were published, it was designed not as a conventional tank, it should incorporate advanced digital technologies and a new 140 mm gun. For reaching a higher level of armour protection by having the same weight limit as