Travel Quiz: Why do I like the bottom of my door scraping the floor?
Keeps out..bugs, dust, noise, snakes and unwanted love notes.
If you are in your room, you will know if someone opens the door. Particularly useful if you are listening to music or watching video with headphones on.
Lawrence is correct for the bugs. Adapting to Africa is to know the rules have changed. Here in West Africa they have Malaria, and I do not want to be bitten by mosquitoes that carry the malaria parasite, so I need to stop drafty doors, this door stops malaria carrying mosquitoes in Africa, while not such a huge deal in Guatemala where malaria is more rare. NOTE: Malaria is not going to kill me, it is an annoyance to an aware person, I had malaria in Lome, Togo a few years ago. It does kill small babies when the mother does not recognize the baby has malaria. There are 13 plus cures for malaria, and growing.
I would never take anything to prevent malaria, it is low level poisons. And, when I had malaria in Lome, Togo, they gave me three intravenous sacks, in 3 days, and that killed it, I would allow the locals to choose, they know their local parasites.
Years ago, we took Fansidar, anti-malarial on our first trip to SE Asia, but after reading the contraindications, we threw the rest away and never took it again. "IF" you live near the beach, there's aways a nice breeze, further inland or in the mountains malaria is more prevalent, but all non salt water can be a incubation area for those pesky moZies!