So these guys are the Cultists I am using for my Iron Warriors. Evidently they aren't GW's offereing - which I like, but dont fit as well with my IW's aesthetic.
If you read some of the Black Library books that feature Iron Warriors, you'll hear about them picking up a variety of stragglers; from prisoners to militant fanatics - and very often they aren't given very glamorous tasks (like walking into enemy fire to identify where guns are mounted, or clearing a minefield by hand...). I like to think these guys were part of a worlds militia that was brought under heel and they decided to paint some hazard stripes on their armour and try and join the IWs.
The models themselves are from the Brothers of Iron Kickstarter and I got a couple of dozen guys and a tank for about £30. You can now get them directly from Ramshackle Games. Size-wise they are a bit smaller than a normal IG, but lets be honest, those models are out of scale really (if an SM is supposed to be 8 feet tall, that would make IG about 7 feet tall?) - so next to a CSM, they look great.
Quality-wise they are so-so... I quite like the poses, but the sculpts are relatively basic and casts leave a bit to be desired, but they can be cleaned up well and you do have to remember - they are coming from a small independent company and not GW. Still - for throw-away high-volume Cultists, they are fine.