Helps reduce “cant error”: One of the most common sources of error at long distance is the rifle being tilted sideways. The bubble level gives you a way to check alignment (scope reticle + rifle) visually.
Lightweight and small: At only ~14 g and just over 2 inches long, it adds minimal weight and bulk.
Easy to install: Can be mounted in different places (in front of, under, or behind the scope) depending on your rail setup. Durability: Being aluminium and made for outdoor use, it withstands typical field conditions reasonably well. It’s shock-proof enough for “real-fire calibre” use (as per vendor specs).
Long-range rifle shooting where even small cant errors can lead to large deviations downrange.
If you shoot over varied terrain (slopes, ridges) and want to ensure repeatable alignment each time.
For hunting, where you move around, set up quickly, and need to ensure the scope is level without carrying large leveling tools.
For competition shooting where consistency counts.