One aspect that pushes the Bunker’s life is that it is a fully sealed dropper post. Dropper posts typically have two holes on the bottom, allowing air to exit the chamber as the post is compressed. Turnon claims that things you don’t want leaving the dropper post can also exit with this air, such as grease. While a dropper post is relatively protected inside the seat tube, moisture and debris can be pulled back into the post when extended. Turnon uses a dual air chamber system to replace these holes, fully sealing the bottom of the post. At the top, Turnon uses what they call the “best dust cover” available for a dropper post, while remaining low-friction. Ultimately, this is why Turnon Components can call their dropper waterproof.

https://theloamwolf.com/2024/08/12/review-turnon-components-bunker-dropper-post/