CIPA 36300 Wedge Base Auto Dimming Rearview Mirror with Compass and Map Light Add the convenience of auto dimming to reduce glare from headlight of vehicles approaching from behind Installation is easy  attaches to existing windshield button (new button also included) Made in the USA and FMVSS 111 approved Features a digital self-calibrating electronic compass and dual map lights Save an average of 50% over a stock replacement mirror