[Wide Compatibility] This quarter-turn seatpost mount is compatible with Garmin Varia Rearview Bike Radar, for Varia RTL510, for Varia RTL515, for Varia RVR315. It is widely used on road bikes with 27.2mm, 30.9mm, and 31.6mm seatposts, helping you keep your Varia radar or taillight on your bike regardless of the terrain. [More Versatile] Compatible with Varia Rearview Radar, for Varia Smart Bike Lights. [Durable Construction] It is strong enough to keep your Varia radar or taillight on your bike regardless of the terrain. [Safe and Secure] We are confident that upgrading to a TUSITA Varia seatpost mount will give you peace of mind knowing that you have chosen the best way to securely lock and perfectly position your Varia radar or taillight on your bike, allowing you to focus on your goals, whether it's having fun or riding fast, or both. Color: Black Material: Plastic Package Contents: 1 x Bicycle Seatpost Mount 3 x Gasket