There’s no question that Dragon Door has the gold standard of kettlebells.  If you want to use the bells that RKC Chief Instructor Pavel Tsatsouline uses, Dragon Door bells are the route to go.

If you have found a bell you want to purchase somewhere other than Dragon Door, my advice is to make sure it’s cast in one piece.  I don’t know about you, but I wouldnt want an iron ball over my head attached with a welded handle.