For sale is a Giant Dropper post. It will certainly fit on numerous brand names of bikes including specialized, Kona, trek, fuji, and numerous others is is 30.9 mm in size and has a total length of 350mm. This is an "considerably adjustable" design, meaning you can stop the post in any position, like KS and Rockshox dropper posts. It was purchased new this spring, but I got a new bike, and needed a different funky size. New they are $250.