Get some new ones rather than used. The plastic gets brittle with heat and UV so you might as well start from scratch. When I removed the old "frames" with the mirror glass, they just crumbled.

If the switch in the visor fails to turn on the light, remove it and spray it with electrical contact cleaner before buying a new one. Worked like a charm for me!

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2005 Pathfinder LE
2001 E55
1998 M3
1982 320i