The Gitzo GS3512S Carbon Fibre Rapid Column provides you with extra height & is for use with the Gitzo Series 2, 3 & 4 Systematic tripods. For those of you who are not familiar with the Gitzo Systematic tripods, they do not come with a centre column but due to their modular design can be fitted with one for users who require more height & also allow you to hang the camera underneath the tripod shoulder on an inverted column. Compared to older Systematic centre columns, the new design is longer & features new components, including Gitzo's much-improved Power Disc (with head locking screws) & a convenient retractable hook to allow stabilising counterweights to be hung from the column.