only a change in inclination. A platform is located between the main gun and the bridge. The superstructure runs continuously down to the helicopter hangar, on top of which short-range anti-aircraft Crotale missiles were initially installed (being replaced on three ships in the early 2020s with the SADRAL/Mistral system). The ships feature two masts. The main mast has a pyramidal structure which integrates funnels and supports the antenna of the Syracuse military communications satellite system, while the second supports the main radar. Life extension upgrades Three of the French Navy frigates (La Fayette, Courbet and Aconit) were selected to receive mid-life upgrades extending their useful service lives into the early 2030s. The three frigates are receiving KingKlip Mk2 hull-mounted sonar to incorporate an anti-submarine capability, modernized point air defence systems (consisting of two renovated SADRAL launchers, removed from the retired Georges Leygues class, and operating Mistral Mk3 SAMs/SSMs) as well as other improvements including the ability to carry the latest version of the Exocet anti-ship missile and CANTO anti-torpedo countermeasures (initially fitted first to La Fayette when she received her upgrade in 2021–22). The upgrades increase the displacement of the ships by some and will permit the three ships to operate through the 2020s and be retired between 2031 and 2034. The first vessel, Courbet, began her conversion refit in October 2020. She returned to sea in June 2021. In October 2021, La Fayette began her planned refit and in November 2022 was declared operational again upon its completion. In February 2023 Aconit, the last of the frigates to be upgraded, began her life extension refit. , the other two vessels of the class (Surcouf and Guépratte) were scheduled to undergo more modest structural and technical upgrades (with the elderly Crotale SAM to be removed), and be withdrawn from service in 2027 and 2031 respectively. With somewhat reduced general purpose capability, it is anticipated that the two ships will be re-assigned to offshore patrol duties for the remainder of their service life. From 2024 the La Fayette-class units will be incrementally complemented, and eventually replaced, in first rank functions in the French Navy by the FDI-class frigates. Ships Export Al Riyadh class: Saudi Arabia The three Al Riyadh-class ships are an expanded anti-air version of the French La Fayette class, displacing about and extended to in length. The ships' combat systems are produced by Armaris (a DCN/Thales joint venture) and