 On 20 December 2007 the contract was signed with Dutch-based Damen Schelde Naval Shipbuilding for four ships at a cost of around €467.8 million.While the first two vessels were built at the Vlissingen shipyard in the Netherlands, to save cost and speed up completion the remainder of the class were assembled at Damen Schelde's shipyard in Galati in Romania.The Thales I-mast is a separate, air-tight module which was built separately from the rest of the ships and then bolted on once complete.