Rear-approaching headlight glare can wreak havoc on your night driving vision. You'll be left alone in the dark with the fast moving hazards of the road. Ensure this doesn't happen with the Gentex 2a Auto-Dimming Rear View Mirror. The Gentex 2a Auto-Dimming Rear View Mirror uses high-tech sensors to detect offending light. Instantly, the mirror eliminates dangerous glare with its "intelligent" circuitry leaving your vision intact. What's more, less glare means less eyestrain and driver fatigue.