The ZTZ99 is the most advanced main battle tank (MBT) of the PLA. The ZTZ99 provides a significant improvement in firepower, mobility, and protection compared to older Chinese-made tanks. Some of the ZTZ 99 ' s technologies have been used to upgrade the less expensive ZTZ96 MBT. The hull of the ZTZ99 is very similar to that of the T-72, but is about one metre longer. The turret and hull are of all-welded steel armour construction. The front arc on the turret can be added with a layer of composite armour, or arrow-shaped spaced add-on armour modules. The armour package is of modular design, enabling damaged sections to be replaced or upgrades installed throughout service life.