ya the major ones are vape pen, medstick, medastick, thc stick, and cannabee. everything but cannabee is all interchangeable. omnicron probably has the best pen type, but the best cartridge in strength is by far medstick. medstick pens are also really cheap at themedstick.com. a medstick cartridge + omnicron pen is probably the best combo, but i would reccomend trying it with the cheaper medstick first to see if you liek it. doing ecig for weed is good and will keep your medicating going, but really isnt a total replacement for smoking. i have to say vape pen is major weak, most heavy smokers wont get a buzz from it. the pen are also way over priced, wouldn't waste money on it.