Can you please explain me the sachse-mohrs theory of strainless rings?

To explain the stability of cyclo alkane beyond cyclo pentane sachse and mohr proposed the new theory that such ring which is absolutely free from strain if all the ring carbon are not in same plane. If the ring is assumed as a puckered condition, the normal tetra hedral angle of 109.28` is retained. And as a result the strain within the ring is released. Cyclo hexane can exist in two non polar strainless form (i)chair form and (ii)boat form.