Clear as glass

I was out and about a while ago and noticed this on the commercial van next to me at a stoplight:

I have no way of knowing whether the crackling running through the skin is on purpose or the result of weather. But I thought it appropriate that a glass company might remind potential customers of cracks in glass.

Also, I don’t know what a “fenestration system” is, exactly (maybe something more complicated than your odd window?), but when I hear that word, I always think of defenestration, a murder method favored by Czechs down through the ages.

But that’s just me.