This adapter allows you to use an 808 threaded battery with a 510 threaded cartomizer. Just screw the adapter onto your battery before screwing on a cartomizer.
A nice add on.Review by SLon 5/23/2014I bought one of these a few months ago. They do exactly what they're supposed to do. I use it to vape carts from another brand that has nice flavors but absolutely horrible batteries.