So essentially the red portion is that non polar hydrophobic region of those phospholipid, the tails. And these blue sections are basically those polar heads. So we have one side, one leaflet, and the other side the second leaflet. And so this is the bilayer membrane, this is the internal compartment and it is separated from the external compartment by this bilayer membrane. Now the question is, how do we build these liposomes? Well, if we want to build a liposome that is about 50 nm in diameter, this is the method that we have to follow.