Designed to be used on the 190pro series tripods, manfrotto's innovative system means you can quickly level your photo or video head without needing to make time consuming adjustments to the length and angle of each single tripod leg. One of the most common problems in still photography and, above all, video has been resolved by manfrotto, thanks to the use of a 50mm diameter levelling half ball mounted at the top of a tripod centre column so as to make the angle of the top plate independent of the rest of the tripod. Locking and unlocking of the half ball is via a turning grip on the bottom of the centre column, which can be removed during fitting of the column to your existing tripod. The half ball mounted plate has a male 3 8 screw for attachment to a photo or video head, and a bubble spirit level for added ease of use.