App takes some basic info from you, asks for your shot measurements from bulls-eye and tells you which way to adjust your MOA scope or AR style peep sights, and how many clicks. enjoy. Great for rifle shooters who need to quickly zero a new scope or get their current rig set up for hunting season. Also works great for AR style peep sights. App calculates the required adjustments while shooting from any number of yards (I recommend starting at 25 yards, then 50, then 100 for a good accurate zero. Compatible with 1/4"MOA, 1/8"MOA, 1/2"MOA and 1"MOA scopes.