The Manfrotto 500BALL & 500BALLSH 100mm Half Ball Leveler w/3/8" Screw for 100mm Bowl Tripods is designed to facilitate quick leveling of 100mm bowl tripods such as the 3141, 3190, 3191, 3192 & 3193 tripods. It can also be used with the Gitzo G-1424 100mm Bowl Interface Adapter to provide an economical and low profile leveling base with any of the Gitzo Series 4 & 5 "systematic" tripods (which feature an interchangeable top plate that accepts rapid or geared center columns as well as leveling bases).