The reason that I stated “possibly” in regards to the sale is because currently, only Russian news sources have this information; no US site has posted such information yet. Nevertheless, RIA news is considered a very reliable website, and they are quoting Izmash, themselves, so there is a big chance that such sales may indeed be taking place. To read more regarding the sales, please see: U.S. Police To Buy Izhmash Shotguns.
The Saiga-12S (the weapon currently in question, no exact version specified), is an AK-based 12 gauge semi-automatic military shotgun, developed for use by Russian Special Forces and Law Enforcement. Due to its Kalashnikov based design, the shotgun is highly reliable and effective. The weapon has a weight of 3.6 kg and can accept almost any kind of 12 gauge ammunition.
The Saiga-12S has rails for the mounting of various optics, lasers, and flashlights. It uses box or drum magazines of 2, 5, 8, and 10 round capacity. The stocks are made of black fiberglass-reinforced poly-amide, and the butt-stock can be folded for easy storage. Saiga-12 (not the S version) shotguns have been imported around the world, and are quite popular with US civilians.