I just posted a thread about how rugged the Provari is. In it I mention madvapes 510 DC carto that figures out to be 1.6 ohms. I just measured it on my Provari and I got 1.7 ohms. I can't go much over 4.3 to 4.6 volts but I really never need to. I use it at about 3.6 to 4.1 (more on the lower range) and get a great hit all the time. My main problem with cartos, tanks, and atty attachments is having to deal with leakage. These cartos just don't leak. I fill them until the liquid actually pools up in the neck and throw the mouth piece back on. The less crap I have to deal with to get a good hit the better and these just plain work. Try one out (Madvape part #3125). Unless your peaking out on the voltage, you'll love em.