There is a forum post for sigelei Zmax V3 and V5 if you would like to read more. I like my MVP butI wanted a tube. I debated the SVD, Vamo and sigelei. The sigelei seemed to be the best built and least complaints about button failures. All stainless, good machining and threads. I got the round top which has Provari styling. The flat top is different. Once I figured out the menu and how to set it, I have been real happy with it. I bought 2 18350, 2 18490 and 1 18650. During the work day, I use 18490 and carry a spare. Weekends I use the 18650. Sometimes I use the 18350s and I could stack them if I wanted that much power. I worried about the gap in 18490 or 18650 mode but it isn't an issue. I didn't like how the SVD outer shell just ends over the inner shell.