So, I've heard a lot of people talking about the doublers, and recommending them. So, how do you go about adding the nic to them? Do you add unflavored nic? Or do you also get the same flavor juice from tv? Also, what nic level juice do you add to them to make a juice with the nic level you like? I usually go between 18-24 mg of nic. How would I go about making the doublers a nic level of 18-24 mg?