Ok cool - why do you say I'd have to wait? Are they not based in the US? (which is fine, I just want to make sure I have the right expectations.
Fast Tech is a legitimate online source based in China, not too different from the US Amazon. They sell a lot of things besides e-cig gear. Some stuff is legit/authentic brand name (it will advertise as such); some will be advertised as "xxxx-appearing" which hints that it is a clone or copy of the item. Orders can take anywhere from 3 - 4 weeks because of shipping. Some items offer free shipping. I believe Li-Ion batteries are NOT available for sale to USA customers by Fast Tech because of fire hazzards during shipping.
I worked for a vape shop for a year in 2014. We sold eGo and Evod kits, single batteries, chargers and wall adaptors. At one point during that year the director of operations for our chain decided to discontinue sales of the smaller " tailess" eGo chargers (like you desire to use) because they were generally considered to be of poorer quality like IZAN said. There was also the belief that the tailess were usually the culprit for fires and explosions. I can't back that up by any hard evidence.
However, statistically, most ecig explosions occur during the charging process.
According to this list:
E-Cigarette Explosions: Comprehensive List
There have been 50 major incidents this year (2016) alone and that's just the ones which make the news. They also go on to say...
"It is interesting to note that the nature of e-cigarette explosions has changed over the years. The FEMA document cited above suggests that approximately 80 percent of e-cigarette explosions happen during charging."
Personally, I would never use a Li-Po or Li-Poly battery for an ecig. These are not a safer chemistry battery, and if hard-shorted they have a much higher chance of resulting in a fire/explosion compared to a safer chemistry battery like an IMR-hybrid 18650. This means I choose to use a "mod" which uses external/removable batteries. They are safer in use and safer during charging; they may overheat and release hot gas, but are not likely to burn or explode. Read the article I linked to above.
Deeper Understanding of Mod Batteries Part 1
- For those who want to learn the differences between IMR, IMR/hybrid, ICR, and LiPo batteries.
Battery Basics for Mods: The Definative Battery Guide for Vaping
Mooch's Recommended 18650 Batteries