Observation window hive bodies allow easy checking of your hives. The window allows an easy peek at your center frames, so you can observe your bees without disrupting the colony. Also helpful in the winter when you don't want to open your hive.
The latches hold the door securely over the window and the bumper at the base keeps the door in place, reducing the chances of sliding when moving the hive body around.
The observation window is also great for showing off your hive to friends or family without having to worry about exposing them to the hive.