Ok so you have landed on this page because you are confused about cartomizer choice? well there's no need to be confused at all it's quite simple. First off the most important element to your choice lies with your battery. That's right your battery is what powers the cartomizer so you need to select the correct cartomizer otherwise you may put too much strain on either the cartomizer or the battery.
Here is a rough cartomizer guide
Standard Classic E-Cig battery
Mah rating: 180/280mah
Cartomizer choice: Size X Single coil 2.5ohm
We have found 2 to 2.5ohm single coils to be the most effective and least drain on these types of battery.
Mini Ego battery
Mah rating: 350/450mah
Cartomizer choice: Single X or XL 1.7ohm.
Although Dual Coils can be used they will drain your battery a lot quicker and result in cycle loss due to constant recharging.
Ego 650mah +
Mah rating: 650/900/1100mah
Cartomizer Choice: Up to LR 1.5 Dual Coils
This is where things start to heat up as at 650mah+ you get to choose LR 1.5ohm Dual Coil Cartomizers without having to worry too much. Some times we get asked are ego batteries designed with LR 1.5 DC Cartos in mind? not really, but at the price of £10 or there abouts it's not too much of a worry if you go through a few batteries, after all a packet of cigs is over £7 in the shops, so all things considering not anything to worry too much about cost wise. At 900mah you will get a decent amount of vaping time even with low resistance cartomizers and although single coils with a standard resistance may be used, there really is no need to do so, just grab a few batteries and rotate them, and when they're done recycle / dispose of them safely and buy a few more!
The next step is your mods and IMR batteries, which is a whole other story. A Variable Voltage mod (VV) and a high capacity battery, such as an IMR battery will allow you to use most cartomizers at a higher voltage without putting too much strain on your battery. Something to be researched and considered at a later stage of vaping.