For $E \subset \mathbb{R}$ and $\epsilon >0$, $\exists$ $(a,b)$ s.t. $\theta(E \cap (a,b)) \geq (1-\epsilon)|b-a|$ ($\theta$ Lesbegue Outer Measure)
For a set of positive measure there is an interval in which its density is high, $\mu(E\cap I)> \rho \mu(I)$