CIPA 36200 Wedge Base Auto Dimming Rearview Mirror with Compass 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 bright integrated LED digital display and self-calibrating electronic compass Save an average of 50% over a stock replacement mirror