Just thought I would share my experience with the Provari and dual core clear cartos. I run the Provari at 3.3V-4.7V and just at 3.9 it seems to be hot like at 5V. If I set it any higher than 4.7 I get the E2 error. The taste and vapor production is excellent. The only issue I have is that it drains the batterys. If I vaped heavy all day I would get about 6 hours with the AW18650s and the cartos gets warm. I am a big cartos fan and I was using Boges and I have went to these for the best quality and price.