Sorry, I don't have a camera that'll plug up to Windows 7 and get a photo online at the moment.
I can tell you that the 510 threads are recessed up inside an outer sleeve that is the same diameter as an eGo battery.
To extend the threads for use with mods that don't like eGo specific stuff, I'd recommend bridging a
510>901/808 adapter to a
901/510, or stack two
510>510 extensions, or some other combo. That would make anything 'eGo' fit pretty much any 510 device out there.
Another option is to grab a
gooseneck.
If your mod is 901 native...chances are all you'd need is the 901>510 adapter...as this one is long enough on its own to clear the bottom of the sleeve which is intended to cover the 'cone threads' on an eGo style battery.