The class is built on the experience gained from the Absalon-class support ships, and by reusing the basic hull design of the Absalon class the Royal Danish Navy have been able to construct the Iver Huitfeldt class considerably cheaper than comparable ships.[12] The frigates are compatible with the Danish Navy's StanFlex modular mission payload system used in the Absalons, and are designed with slots for six modules. Each of the four stanflex positions on the missile deck is able to accommodate either the Mark 141 8-cell Harpoon launcher module, or the 12-cell Mark 56 ESSM VLS.[13] The Peter Willemoes passed the British Flag Officer Sea Training test in 2015.[14]