You can get them
here, or
here, or other places. Most people will recommend the
LR Boge soft cap ones. you can get them
prefilled or blank. Most people will recommend blank ones (but I liked to get them prefilled and then refill them myself, it seemed like they worked better/wicked better)
YOu can refill them a few ways. I like the
condom method, but if you get the soft cap ones you can pop the cap off and drip into the filler like
this.
edit Almost forgot pros vs cons:
pros

:
• very convenient to carry around
• you can fill some up at night and take them with you the next day - no more topping off
• they hold more liquid, so last longer per fill than cartridges
cons

:
• they are meant to be disposable, so can only be refilled a few times before they quit working well
• you won't know they've gone bad until you fill it and try to use it... waste of juice
• you have to keep buying more and more of them
• if you singe the filler, they are ruined - but you might not notice the filler is singed until you refill the next time... waste of juice
neither here nor there:
• most people say they prefer dripping or carts for flavor and vapor, I still say cartos are the best for both.