That one thing would undoubtedly be my first REO Grand. It took my favorite vaping, dripping, from being a two-handed activity I only was able to enjoy at home in the evenings, to something I can do one-handed, from wake-up to bedtime, even when driving, with a day-long 6 ml bottle and 18650 battery, in a palm sized package smaller than a pack cigarettes, with no need to carry anything else. It lets me continue to use my disposable drip attys and even acts as a tank and mod for my unpunched cartos, but the ultimate dripping on it is with the bottom-fed, flood-free, Reomizer 2.0 rda. It's my end game, a Snap-On-like, commercial-duty grade tool I use all day, every day--so I bought a backup.