Using the Garmin Varia RTL515 is simple. First, pair it with your Edge bike computer, smartphone, or other compatible devices. You'll start getting alerts when a vehicle approaches from behind. When using the Varia app, you can see graphics and get extra alerts about the position and speed of approaching cars. For mounting, just attach the device to your bike's seatpost. Make sure it's secure. When riding in a group, switch to peloton mode to avoid blinding other cyclists. As for battery life, if you use the day flash mode, you can enjoy up to 16 hours of use. In solid mode, it lasts about 6 hours. Charge it when the battery is low. Keep the device clean by wiping it with a soft, dry cloth. Avoid using harsh chemicals. Check the mounting regularly to ensure it stays in place and functions properly.