Lol..they are not there to clean the rain from the headlights...they are just there to clean the dirt and grime buildup that gets on the headlights if you drive in bad winter weather with salt and slush on the roads.
People who have driven through bad winters know what I mean. There are times when you have to clean your headlights to see. Well, the wipers will do it for you, so you dont have to get out of the car. Hope this helps.
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1993 GT/AOD
'93 Mustang GT