The S-300F "Fort" (Russian "С-300Ф Форт", DoD designation "SA-N-6", "F" suffix for "Flot", Russian for "fleet") was introduced in 1984 as the original ship-based (naval) version of the S-300P system developed by "Altair" with the new 5V55RM missile with range extended to and maximum target speed up to Mach 4 while engagement altitude was reduced to . The naval version utilises the TOP SAIL or TOP STEER, TOP PAIR and 3R41 Volna (TOP DOME) radar and utilises command guidance with a terminal semi-active radar homing (SARH) mode. Its first installation and sea trials were on a Kara class cruiser and it is also installed on Slava class cruisers and Kirov class battlecruisers. It is stored in eight (Slava) or twelve (Kirov) 8-missile rotary launchers below decks. The export version of this system is known as "Rif" (Russian "Риф" – "reef"). The NATO name, found also in colloquial use, is ""Grumble"".