>> this is low priority relative to the core mission that spacex has, but i think it may -- i think it might help if i created a prototype. and sort of helped get things going in that way. >> get things going. look at the pictures and the diagrams of this. first of all, this is what they say it will look like. but -- >> it's like a helicopter, train combo? >> it's in a tube and you sit in chairs and there's 30 or so of you in the capsule. at the front, you have a compressor fan. i'll show you the diagram for that. in the middle, you have the passengers, and in the back you have the batteries, and you're going at the speed of sound through this tube. and here's something i know you'll want to take home and study closely. >> yeah. >> that is the compressor. >> this is the one that makes my head spin. what is this?