Started with cheapo starter kit I found at Walmart. Yuck. The strongest was 1.8% and way too weak. Then some juice came out onto my lip about half thru first day. When I needed to swap it out for a new cart I saw that the end had turned brown! That can't be good. The second one was starting to leak too so I changed it out. Lucky for me the rest of them were fine (I had bought a box of refills that cost the same as the kit and had 5 in a box) Lucky I guess that kit was only $22. It came with 2,batteries and a USB charger plus 2 ends. The only vapor to come out was if you didn't hit it hard and just puffed into mouth and blew right out. How lame is that? Made in China I see now. Glad I picked a new company that makes it all in the USA!