Hi All..I was given a kayfun v4..yes given. I had no idea how much they were until I looked it up. Took it apart and put it back together about 10 times after many youtube vids. Bought what I needed to build a coil. Again after many youtube vids built my first coil and after some trial and error have success. vaping with an istick 20 and the kayfun v4 obviously. 1.5 ohms and 8 watts. What a great vape.