Amazon.com: Mountain Bike Seatpost Dropper Remote Lever, Universal Adjustable Bicycle Seatpost Remote Lever Shifter with 2 Wrenches for 22.2mm or 24 mm Mountain Handlebars : Sports & Outdoors
Amazon.com : 27.2 mm Bike Suspension Seat Post: Bicycle Seatpost Shock Aluminum Alloy Absorber Damper 27.2 30.9 31.6 mm Seat Post for MTB/ Road/ BMX Bike 27.2 mm : Sports & Outdoors
Suspension Tech: Why your dropper seatpost isn't working - Bikerumor