This afternoon I discovered that this little thing has one of the best designed cartridges I've ever encountered. Check it out:
Twist off the cartridge from the atomizer. Take a paper clip and stick it through the hole in the bottom of the cartridge. Up comes a little plastic piece and the filling. The plastic thing is shaped like a tulip vase and holds a pinch of aquarium polyester filter material.
Pull out that polyester piece. Easy to wash and rewet, or ... to use your own liquid, which is exactly what I've been doing now. I get much better taste and even better vapor with my homebrew stuff. The tulip vase piece is about the neatest arrangement I've ever seen. And it does a pretty good job of keeping liquid out of the mouth (but not completely on occasion).
Some time ago, I bought an entire bag of polyester filter material at a local pet store (find it near the fish aquariums). Dirt cheap stuff and it's used in some commercial cartridges. A tiny pinch of new filter could easily be stuffed into the plastic piece, soaked with fluid, and placed back in the cartridge. I've done this several times now. These cartridges appear to be endlessly resuseable!
Now, the question is how long will the atomizer last?
$17. Are you kidding. I've loving this.
BTW: Heavy use today; battery lasted only half a day.
I've been using an M401 for almost a month now, and ordered a few of these packs from dealextreme.com to try (and to give as gifts if I found they were even halfway decent - which they aren't). One interesting thing I found is that Tropical Bob's observation was spot on (as usual).
The inner cartridge (tulip-vase shaped) is an awesome replacement for the stock 401 piece. It rides a little higher than the OEM version, and was difficult to seat the cart to the atomizer all the way, so I had to shave about .5 mm to get it right (this also trims off all the foil). I replaced the cotton-ball filling with Fluval (common replacement filler - search the forums), and put in a straw mod (search the forums for this also, there are several references to this), and it's a fantastic upgrade. Since I'm not using the filler piece anyway when I dip (yes, dip, not drip), the cig makes a decent alternate to chain vape at my desk while my M401 is cooling down.
Although the eHealth and the M401 are thread compatible, the threaded part of the eHealth battery doesn't extend out as far as the M40x batteries. This means I can use the eHealth atomizer with my M401 batteries, but not the other way around. The eHealth case does charge my M401 batteries, but the eHealth atomizer doesn't work with my USB passthrough very well. I haven't spent the time to figure that out yet. All in all, well worth the price, imho, for a mediocre alternate and the cartridge upgrades.
Q4mK