The Manfrotto 500BALL 100m Half Ball Leveller w/3/8 Screw for 100mm Bowl Tripods is designed to enable quick levelling of 100mm bowl tripods such as the 3141, 3190, 3191, 3192 & the 3193 tripods. It can also be used on the Gitzo G-1424 100mm Bowl Interface Adapter to provide a reasonable and low-profile levelling base with any of the Gitzo Series 4 & 5 regular tripods (which feature an interchangeable top plate that accepts quite quick or geared center columns as well as levelling bases.