[Al-Khwarizmi]

I didn't know the name either. Yeah, I'm spoiled by them in Spain (at least in my region, pretty much every residential house or building has them) and I typically sleep too little when I'm elsewhere due to lack of them. No other alternative I have seen comes even close when it comes to making a room really dark at night.

I just call someone to fix them, though. It's quite a dark art for those of us who suck at DIY.