Easton EC90 20mm Setback 350mm Carbon Seatpost. Perfect form, flawless function, and feather light construction are what the Easton EC90 20mm Setback 350mm Carbon Seatpost is all about. The EC90 utilizes full carbon fiber construction including the upper and lower clamping plates to keep the gram count to the bare minimum. And of course, this post is plenty strong, too. By incorporating RAD Relief Area Design and TaperWall technology, the EC90 has been intelligently designed to distribute stress along the length of the post. And for those whose position demands pushing the saddle back, the EC90 features 20mm of setback.