When you buy a Nautilus it comes with a backup glass tank in the box. Got this bottom piece (along with the top piece) to go with it. Now i have 2 Nautilus and it cost me $34. Sure this is not an authentic part, but, gotta say, some of the best work I've seen in a clone. Airflow is exact same as regular Nautilus (all 4 settings with no whistling when inhaled), no leaks and durable.
On this one, I've noticed, there is a small pin on top of the spring that makes contact with the atomizer. In this aspect, the unlimited ecig piece is better that the actual Aspire part. I have noticed much less cleaning out of this is needed. With the Aspire part the slightest moisture seems to weaken the electrical flow to the atomizer. The pin on this one is a clear fix.
Also I live in Colorado. It said it could take 10-21 days to get to my door. Got here in 9. Thanks guys. Will be buying another Nautilus for my wife and will be ordering more top and bottom pieces soon.