OOps first link didn't post correctly... Try theses, much cheaper... :) (not sure about fish bubble stones)
http://silversurfervap.com/ceramic-flavor-disc.html#
Copy of a post I made on another forum...(grasscity)....
Shatter/Oil/Budder/Wax RBD e-cig-vape MOD.
Required..
1. Any dual coil RDA ( one with adjustable air flow would be best )
2. Any porous inert ceramic disc :- ( a couple of examples )
a.. http://silversurferv...avor-disc.html#...