To guard against glare from headlights behind you, what should you use?

Using a day/night mirror is the best choice to guard against glare from headlights behind you. This type of mirror is specially designed with two reflective surfaces that can be easily adjusted. When bright headlights from vehicles behind you create glare, the mirror can be flipped to reflect less light, thus reducing the brightness and making it easier for you to see the road ahead without being distracted or momentarily blinded by the glare.

In contrast, a regular rearview mirror does not offer any glare reduction features and will reflect all light directly, which can be problematic at night. A tinted mirror might help somewhat, but it does not have the adjustable capabilities of a day/night mirror. A blind spot mirror is primarily intended to assist with visibility in blind spots rather than reducing glare, making it unsuitable for this specific situation.