Brand New Crank Brother's Highline Dropper Post w/ remote.
30.9mm diameter.
Would love to have used it, but the frame it was intended for has too short a seat tube to allow it's use.

Never ridden.
Brand new.

My photos aren't so great, here's a better idea of the post.
https://www.crankbrothers.com/produc...ne-dropper-125