i have a question for you
if you get a cheap mirror and use some offbrand cleaner (not generic windex or not spray-nine)
do you think the mirroring might start flaking or the cheap chroming might come off ? cheap plastic-crome'ed stuff starts flaking in 2 yrs even if expertly cared for, did you know ?
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buy OEM. when cleaning don't use unusual cleaners. don't rub dirt into it, rinse off first
you'll save money by not having to pay to replace the thing multiple times and it will look allot better
a cheap mirror might break when you tighten it or even fall off - you'd be left not passing inspection going down road no mirror
cheap? it will start moving around. you tighten. 1wk later happens again. tighten finally it breaks just after warranty.