I love my VFL kit and got 5 blanks and 15 Kamel Menthols and 1 30ml bottle of Kamel Menthol juice to start. I have been vaping for about 21 days and have refilled both the blanks and the pre-filled multiple times with no problem. I like to drip the juice into one of the rubber protection tips and then insert the blank or used up cart slowly forcing the liquid into the cart. When you see juice start to come out the top then you are full. There are several great videos on youtube on how to do this. So far I have not had any of my carts seem to lose vapor strength and the refill juice tastes better than the prefilled carts IMHO.