For installation of monsoon shields (and a whole bunch of others, quite often) VIRM says
"In-service requirements for condition and performance must be met."
What does it actually mean?
The specific question I have though is, if there are any transparency requirements, can it be opaque (I think I've seen ones made out of metal, for older cars) for monsoon shields,
If the area of the side glass where monsoon shield overlap needs to meet 35% VLT combined etc.