chirality of conformations of cyclohexane

How is the chair form of cyclohexane achiral?
I don't think it has any plane of symmetry. I have tried very much to find the symmetry in it, but I cannot figure it out.




The figure shows the symmetry elements in the chair form of cyclohexane. (From molecule-viewer.com ). The point group is $D\_{3d}$.


There is a $3$ and a $6-$fold rotation axis through the centre of the molecule, $3$ two-fold axes between opposite sided and at the mid point of the CC bond, and $3$ (dihedral) mirror planes that bisect the two-fold axes.


[![chair cyclohexane](https://i.stack.imgur.com/49oLD.png)](https://i.stack.imgur.com/49oLD.png)


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