They were archers who could use either the right or left hand, both to sling stones and shoot arrows from a bow. They were Saul’s relatives from Benjamin:

Either three years' famine; or three months to be destroyed before thy foes, while that the sword of thine enemies overtaketh thee; or else three days the sword of the LORD, even the pestilence, in the land, and the angel of the LORD destroying throughout all the coasts of Israel. Now therefore advise thyself what word I shall bring again to him that sent me.