The K9 Thunder was developed in the late 1980s to replace the M109A2K, also known as the K55, to meet 21st century requirements. Key operational requirements included a higher rate of fire, longer range, better accuracy and faster into and out of action times. This artillery system entered service in 1999.K9 Thunder has a weight of 47 tons, a length of 12 m, a width of 3.4 m, a height of 2.73 m. A standard crew includes 5 men: Commander, Driver, Gunner, and 2 Loaders.