E........O

This pen is amazing! I love how discreet it is. The cartridge fits inside the pen rather than twisting on top, so no one can see the oil unless you pull the cartridge out. And the pen vibrates when you hit it instead of lighting up, which makes it even more discreet (the vibration is mellow and not overpowering). This pen hits better than any other pen I've ever tried; it consistently produces big hits. I've had my pen for a few months now and have never had any issues. This pen is a must for any vaporizer fan! You will not go back to 510 thread after giving this a try.