The Centurion class of frigates will replace the Decurion class of frigates over the next 5-10 years. Composed of two variants, a total of 20 of each variant will be constructed. One variant carries the new SURTASS II sonar system, which is an evolution of the SURTASS sonar system, using the latest hardware and signal processing algorithms and thus a quantum leap in sensitivity and enhanced submarine acquisition. The other variant is an anti-air variant carrying more anti-air missiles. SURTASS II-M would instead equip the non-ASW variant of the frigate.