And this can be basically explained from a physics perspective. So basically we can imagine our enzyme initially has a rectangular active side while our substrate is, let's say, some type of trapezoid. Now, when the trapezoid, the substrate shown a red actually goes into this rectangular active side. The rectangular active side changes in shape slightly and the trapezoid, we can imagine the trapezoid also changing in shape. For example, it is basically lengthened. So we see that the substrate as well as our enzyme are not really perfect fits but when they interact within the active side, the enzyme as well as the substrate, they change in shape to basically create that perfect fit.