The range of your sling attack is doubled.
Prerequisite: Weapon Focus (sling or halfling sling-staff).
Benefit: You increase the range increment of your sling attacks to 100 feet. If you have the sneak attack ability, you can make a sneak attack with a sling against a target up to 60 feet away.
*This feat benefits users of the sling or halfling staff-sling, and is the original concept of Weirdo and Xunal on the Homebrew thread of the Paizo RPG website. (Weirdo; Sling Sniper feat)