Why do refrigerant cans have this?

R-134a can. My pet theory is that it provides a predictable blowout location if the can is accidentally connected to the high side of an A/C system. But that’s totally made up on my part.

Could also be a “grab” location for something that rotates the can during label printing.


Pretty much the blowout as well as your supposed to knock it out. Disposable cans have that. The larger tanks have actual reliefs.
Here is what one looks like on R-410a