MECHANICAL DropLoc TECHNOLOGY. The Fall Line dropper seatpost allows you to infinitely adjust the height of the post in a new way. A mechanical brake locks the post in position without having to circulate large amounts of hydraulic fluid. Its lighter, more reliable, and has faster return speeds. The mechanical lock is SPRING actuated, so even if air pressure is lost, the post still locks in any position (but of course the post will not return without help). Now that is reliability!