Amazon.com : AARON - Spring Suspension seatpost - Aluminum Bike seat Post for E-Bike, MTB, - 1.1", 27.2 - 30,9 - 31,6 mm Diameter, 13.8" (350mm) Length : Sports & Outdoors
Amazon.com: Suspension Seat Post, Shock Absorber Post, Aluminum Mountain Bike Seat Post with Protective Cover, for Most Mountain and City Bikes, 27.2 28.6 30 30.4 30.8 30.9 31.6 33.9 X 350mm : Sports & Outdoors
Thomson Elite Seatpost: 30.9 x 367mm Silver - Walmart.com
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Unique Bargains 30.9 to 31.6mm Bike Seat Post Tube Adapter Seatpost Reducing Sleeve Shim Adapter Aluminium Alloy Black - Walmart.com