Although i cannot compare it to the original, the EHPRO V4 has smooth threads, does not leak and vapes like a charm. I see only one difference compared to the drawings of the original: the nut and teflon ring where the 510 screw goes into, cannot be removed. This means that the last parts of the base cannot be separated from each other (the 510 connection part from the turning part under the juice control. It seems that this is different in the EHPRO V4 from the original one. The result is that you cannot change that part so the V4 can be flush mounted on for example a Provari etc. For me that is not a big problem. And maybe only a few of them have this problem (several people mentioned it on the Dutch forum though).
{ From the V4 drawing i'm referring to parts #10 and #11 not getting out of it, preventing me from reaching part #9}
The other thing is that the EHPRO contains machine-oil, or at least the smell of it, more than any other clones i bought. So a thorough clean of all parts of the V4 is very recommended. I rinsed it 3 times and still could taste it. But after 2 tanks of juice it was gone completely
Other than that, this EHPRO Kayfun V4 clone is a very good device. I like it and am happy i bought it.