Widely Compatibility It is suitable for most Garmin tail light rearview radar, such as for Varia RTL510, for Varia RTL515, for Varia RVR315, for Varia RTL 500. It also suitable for Magene L508 Bike Radar Tail Light. Solid and Durable The mounting bracket that fixed to your bicycle is made of high quality alnium alloy material, can be fixed under your bicycle saddle firmly, solve the problem of losing the radar due to unstable fixing on the seat post. Safe Riding this mount allows you to mount the radar under the saddle, it keeps the radar in a higher position than on the seat post, so that the radar sensibly detects arriving cars better, provides visual and audible alerts to warn of vehicles approaching. Quick & Easy to Installeasy to assemble and adjust with the supplied screws and bonus metric Allen wrench, hooks perfectly to the saddle rails and remains stable even on rough roads. Please Measure Your SaddleThe bike saddle must meet the requirement that the center distance of two mounting points is 53-58 mm.