I’ve had my Varia for almost a year now and it is an awesome situational awareness tool. It’s not perfect, there are circumstances when it won’t alert when a car is behind me specifically when it’s matching my speed. If it tells me a car is behind me than a car is behind me. If it doesn’t show a car I instinctively know to check when necessary, sometimes I see a car slowly waiting for the moment to pass and undetected by my Varia.