The 2S1 Gvozdika, (, 'Dianthus'); is a Soviet 122-mm self-propelled howitzer that resembles the PT-76 but is essentially a lengthened version of the MT-LB APC, mounting the 2A18 howitzer. "2S1" is its GRAU designation. An alternative Russian designation is SAU-122 but in the Russian Army it is commonly known as Gvozdika. The 2S1 is fully amphibious with very little preparation, and once afloat is propelled by its tracks. A variety of wider tracks are also available to allow the 2S1 to operate in snow or swamp conditions. It is NBC protected and has infra-red night-vision capability.