The Excelsior Class became the mainstay of the fleet in the late 23rd and early 24th centuries, replacing the older Constitution class as the flagship class. The Excelsior class remains in service today, more then 60 years after if was first launched, through a program of continuous enhancements to the ships systems. The Excelsior class has two major refit variants, the Enterprise-B type and the Lakota type. The Enterprise-B type, commissioned in the late 23rd century, has upgraded sensor and science systems. The Lakota type, commissioned in 2372 right before the outbreak of the Dominion war, brought the weapon and defensive systems up to standard with the Defiant and Sovereign classes. Because the Lakota type has so many upgrades the bulk of the Excelsior Class’ are unrefited to that extent. The Excelsior Class is 511m X 195m and has a crew complement of 750. The standard Excelsior Class armed with 10 Type X Phasers and 4 Photon Torpedo Launchers. The Lakota Type is upgraded with 11 Type XII Phasers and 4 Quantum Torpedo Launchers. Production of the Excelsior continued until the early 25th century. This final refit was armed with 7 Type XIX Phasers, 1 Quantum Torpedo Launcher, and 4 Transphasic Torpedo Launchers. It was also equipped with the first MLSS and was capable of reaching warp 17. The class was officially retired in 2417 after 132 years of service.