Vaporflow and at least 1 other site have the stealth 510-901/808 adapter, they add almost no length to a carto if you want to use it on a 510. One good thing I have found is that when your carto starts to have a difficult draw on your 808 battery even after running a paper clip thru the center to clear it out these stealth adapters drastically improve the draw adding new life to your carto when you use it on your 510 battery. They are pricey at 5.95 but are woth it to me, I have 8 of them. I have 2 mods, an 808 and 510 and use only coolcarts on both of them.