I also have the Smok Zmax not the Sigelei, but one more thing to point out is if you favor the 18650 battery configuration, the Zmax is almost a 1/2" smaller in length and slightly smaller in diameter. I purchased the vamo to use while I'm working but realistically in 18650 mode, it's just a little too large to put in a coat pocket without noticing it ALL the time. The Zmax is a better fit for that. However I am using my Vamo almost exclusively while at home. The heft and bulk of the VAMO is just "comforting" and it performs like the zmax. I love both units. I pass up my Provari most of the time now just because I don't want to drop it and destroy it or something. I love the Vamo for the simple fact that it is inexpensive but still offers you just about everything you could want out of VV/VW unit. This is definitely the best value I have purchased in quite some time. One more thing to note, I have dropped my zmax a ton without any problems with chips, dents, or malfuntions. I have not had the Vamo long enough to abuse it yet, but Im thinking it wouldn't fair as well. Overall the build quality IS much better than you would expect from a $50.00 mod. Threads are nice and tight, nice thickness to the metal, and it looks quite amazing. I have the chrome version but will be buying the SS version for myself very soon!! You can't go wrong with either the Vamo or the Zmax in my opinion.