what types of pellet cookers are allowed in competitions?

I have considered a pellet cooker for a while, as it seems like it may be a real convenience at comps. I don;t want to get into the whole debate of weather they should be allowed at all, just didn't know if there were any rules concerning what types may be allowed, or not allowed and why? I just found someone selling a traeger for a reasonable price, but the only brand i hear people talk about are FEC's. Would love one, but it is out of my price range.