Cartomizers are an alternate way to use your electronic cigarette.  They essentially turn your e-cigarette into a two piece unit, by relpacing the cartridge an the atomizer with a single cartomizer.  Instead of filling your cartridge, you fill the cartomizer, which has a heating coil (just like an atomizer) and poly filler (just like a cartridge) buit in.  They work with all 510, EGO, and T-Rex batteries.

Cartomizers are disposable, and generally can be refilled several times before they wear out.  They do not last nearly as long as atomizers.

How to fill S 510 clearomizers

HOW TO FILL CE2 CARTOMIZERS