Thomson
If you can break a d/h post get the best for your own safty
Have a look at the tests thomson do this is from there website
Original Goals of the Thomson Seatpost Design:
Make the strongest post on the market.
Make a post with the correct failure mode, bend-don’t break.
Make a post with a long life cycle.
Make a post that engages with the saddle and the seatube of the bike in a simple manner.
Make a post that is light while being strong and safe.
We designed the Thomson post to bend above the max line, bend-not break. We designed all of the clamping mechanism to be stronger than the post so that no matter what, the saddle stays with the post in a failure. We received a patent for this failure mode; we call it our bending fuse. Carbon fiber will not fail in this manner. Carbon can be strong but when it reaches failure point it fails catastrophically.