Gitzo GS1320D Series 1 Aluminum Adapter Disc for Center Column - Replaces GS1120D (Black) Used To Attach A Head To The Bottom Of Gitzo Series 1 Tripods Features A Reversible 1/4"-20 And 3/8"-16 Stud For Camera Mounting An Ideal Solution For Upgrading To The Latest Version Of Aluminum Discs And Bolts