Let’s look at definitions of the two words:
Crenelation: A crenelation (from Latin crena, “notch”) is a series of indentations or loopholes around the top of a castle, battlement, or wall—with each indentation being a crenelle (or crenel).
Here are a few crude examples of different types of crenelation:
Bezel: A bezel is a retaining outer rim
Here is a crenelated watch bezel:
When we combine the two terms and apply them to lights or flashlights, we come up with some pretty cool crenelated bezels:
These are often referred to as strike bezels for obvious reasons. Later, we’ll address the uses for and practicality of crenelated bezels.
For now, just marvel at the aesthetically pleasing engineering work!