One common use is for flower boxes and planters. The curved section can support plants outside the window, which is especially useful in apartments or homes with limited outdoor space.
The extra space can also accommodate window air-conditioning units or other equipment. This allows homeowners to keep the security bars in place without having to remove or heavily modify them.
So the curved bottom is more than just a design detail. It combines security, practicality, and decoration, while making the window area more versatile for everyday use.
