This side contains a solution of 20 ML that contains 3 grams of our polymer. So the red dots are our polymer dots. Now what will happen? Well, since the concentration of our solute is greater in this side, then water will tend to move from this side to this side, right? So osmotic pressure basically says well, I need to apply this much pressure on this side of the membrane to stop the movement of that water, to stop osmosis from occurring. So that's what is meant by asthmatic pressure.