This is a guest post written by Morandir835, a regular on V4L's  sub forum on ECF, and an e-cig enthusiast. Vapor4Life sells two kinds of cartos: WOW carts and CoolCarts. Neither is better than the other, as they both have their own set of advantages and disadvantages. It all comes down to personal preference. There are pre-filled cartos  than come with e-liquid already inside them, ready to vape right away. There are also blank carts that you have to add e-liquid to. The pre-filled CoolCart  line uses Premium juices, where the WOW cartos  come with the WOW line of juices. The flavors of these two lines, even if they share the same name, are different. They're made in two different facilities, and the Premium line is a higher propylene glycol (PG) to vegetable glycerin (VG) ratio, somewhere around an 80/20 mix max. The WOW line has more VG, they range in the 73/30 PG/VG ratio (except the WOW VG line, which is 100% VG). A juice gets thicker as the VG balance increases. Any type of juice can be  used in either blank WOW cartos  or blank CoolCarts. It's time to touch up on ohm's law. Volts divided by resistance equals amps. Amps times volts equals watts. The higher the wattage the higher potential for vapor production (vp) and throat hit (th) (this is dependant on the type of juice and its nicotine strength). The higher the wattage, the shorter the battery life, and hotter the carto will get. V4L batts start off above 4.1v on load depending on what charger and what type of batt  is used (to be discussed in a future post). CoolCarts  come in at a medium ohm range, the target is 3.4 ohm but due to fault tolerances they have come in as low as 3.0 ohms (rarely), and as high as 3.7 ohms (also rare). In my tests of 97 CoolCarts  the average is 3.3 ohms. Both CoolCarts  and WOW cartos  use a single vertical coil design. CoolCartos  also hold an average of 1.15 ml's of juice, the lowest I've seen is 1 ml even, highest just over 1.3 ml's (say 1.35 or so). The filling in these is very tightly wound, so thicker juices will take longer to absorb than thinner ones. These carts are called  CoolCarts  because of their higher resistance, and don't run as hot as WOW cartos. These perform  very well for chain vapers  or those who use a USB passthrough  (a 5v  device that will be discussed in a future post). WOW cartos  have a low resistance. The target goal is 2.5 ohms, but in my tests of 172 WOW cartos  the average is actually 2.3 ohms. I have gotten one as low as 2.0 ohms, and seen a few as high as 2.7. That's well within range of fault tolerances though. WOW cartos  have a looser filling, which makes them better for higher VG juice. They also hold on average 0.9 ml's of juice, can be  as low as 0.8 ml's, and as high as 1.1 ml's (very rare). These do run hot, especially when chain vaping or using a passthrough. I suggest getting a drip tip for these if you're planning on doing either. They not only offer  easier removal for refilling, but due to their larger opening provide better airflow which improves th and vp potential. The average battery life of the two cartos, based on 10 runs of each type, on the same batt chain vaping are: King Diamond Shorty  with 3.3 ohm CoolCart - 151 minutes, with WOW at 2.3ohms- 125 minutes King Diamond Regular with 3.3 ohm CoolCart - 208 minutes, WOW at 2.3 ohms- 172 minutes King Diamond XL with 3.3 ohm CoolCart - 299 minutes, WOW at 2.3 ohms- 243 minutes Up next is a post on the different chargers, and more detailed information on the effects of deep cycling a battery. Contact Morandir835 via e-mail at [email protected] or through his page on ECF at http://www.e-cigaretteforum.com/forum/members/51087/morandir835.html.