so what is it really. instead of buying new carts...what is that material and can i replace just that to hold my juice instead of buying new carts. btw i have a ego and i use the mega atomizer type b with the mega cart. since thats how i got my ego when i bought it. so far ive been cleaning out the prefilled ones i got with the kit and using my own juice in them and its working for me that way. but i know it will eventually get burnt out. so i was wondering if there was just a way of replacing that special spongee material in the mega cart for the egos. man i love my ego. and ive been off analogs for a good week now. i know ive been vaping more. but i think this will eventually have me vape less thru time.