it is essentially a gas-operated semi-auto AK47 shotgun in 12ga, 20ga, and .410caliber
go to this site and check it out.
The Russian-American Armory Company is the current importer. Thank the LORD they came along - prices on Saiga shotguns were going through the roof at auctions, due to increasing rarity.
a detailed article on the Saiga-12 exists in wikipedia, copied from a dedicated AK review website iirc.
some happy folks among the FR banglisters have these weapons, and have endorsed them as generally excellent field and home-defense guns
And, as you know, I'm one of those happy folks.
Saiga forums: forum.saiga-12.com
They come with 5 round magazines, but you can get 8 rounders on the gray market, and there are US-made 10 rounders in development by at least three different entities. There's also talk about converting some mags to be drum feed mechanisms.
There's a small but growing aftermarket for these things. I love mine - the reliability of the AK mechanism in a mag-fed shotgun - best of all worlds.