On 18 August 2005 Nykõping , Sweden's fourth Visby -class multipurpose guided-missile patrol craft was launched in preparation for a 2006 delivery. Next year, the vessel will join lead sister ship Visby along with second of the class, Helsingborg , and third unit, Härnösand , in naval service. She will be followed by a fifth and final ship, Karlstad , in 2007. Numerous advanced measures have been taken during design and construction to reduce the radar, infrared, magnetic, acoustic, visual, laser, and wake signatures of the class. As a result of these and other design advances, the class has heavily influenced the U.S. Navy's littoral combat ship (LCS) program. Fitted with a 57-mm dual-purpose cannon, these warships can also carry RBS-15 antiship missiles, type 45 torpedoes, antisubmarine rockets, and a single multi-purpose helicopter.