i don't understand. the threads on the i-turbo bat look the same as my other 808 slim bats (litecigUSA, V2, Magicmist, etc), and the clearomizer looks the same as the V2 liqamax's and Klanger M3's ive used before. i dont understand the compatibility issue.
There are two types of 808 big batteries, the Echo and the vGo. They're both roughly the same diameter, or so I've been told. The Echo batteries have a flat base under the battery threads, while the vGo batteries have a second set of threads under the 808 threading just like the eGo. Cartos or clearos designed to work on the Echo batteries have a flat base where the 808 threading is, while those designed to work with the vGo batteries have a "skirt" to cover the cone threads. If you have an Echo battery you need to make sure any cartomizers or clearomizers don't have a skirt or else you can't use them without an adapter. With a vGo, any 808 threaded carto or clearo will work fine, whether it has a skirt or not.
Thankfully, most items will at least be labelled Echo but it's best to make sure to confirm that before buying. Also, Echo-sized cartomizers and clearomizers hold a little more juice, because they don't have to cut out the bottom portion for the skirt.
And after looking at it some more, the standard OMG mod is crap. It doesn't even have an on/off feature, so you'd have to disassemble it if you pack it up for travelling or you'll kill your battery.
If you really want a big battery for 808's get the I-Turbo kit, a Volt X2 from Smokeless Image or the Revolver iGo kit from NHaler. The I-Turbo kit really is an excellent price for what you're getting, and both Cigeasy and NHaler sell additional Echo equipment. $42.00 for 2 1300 mAh batteries and 2 CE5's is awesome. The X2 is $20.00 for just 1 650 mAh battery, but I still recommend them because I love mine so much. The X2 is also a pass-thru, which means you can vape on it while it is charging. And the Revolver kit is $28.00 for a 650 mAh or $32.00 for a 1300 mAh VV battery and a CE5.
I've also heard great things about the Echo kits from Cigeasy, but they're also pricey as hell due to re-branding.
They're all good options. The only thing I would even look at from V4L is the VV mods. For the price they're asking for the standard OMG mod you could buy a 905 Screwdriver and some clearomizers. At least the 905 has an on/off feature and that thing is 3 years old.