I have a lot of clearos too... my favorite being the iclear16. BUT... the Aspire ET-S blows it out of the water, WITH glass tank, WITH stainless protector of glass tank making it much more portable... tho bigger. The bigger means it holds more juice too.
BUT... if we are looking for a unit that will fit inside a credit card (er... WHY? You can sneak any e-cig on a plane, so not sure who else you'd need to hide it from)... can't help, because I wouldn't want it... what for??
I think maybe because I'm fine with BIG. The only point of small is to have more backups.
He wants to chomp one in his teeth when he rides his bike.