The new Riva's are different than what I ordered a month or so ago. The 510 cartomizers that I ordered won't fit it. I have 306 cartomizers that fit it. My 510 atomizer from my previous kit won't fit on the new 510 Rivas I bought. How am I going to know how to shop for cartomizers?? This is suppose to be a gift, 2 actually, both have different threads ? Anyone have input for me. I'm kind of leary to turn a new user out with these. The old Riva is branded Riva in tiny letters, and the new ones have much larger writing on the battery connector. Is it possible I got the wrong thing. I double checked my order to make sure I ordered 510..