TDC series thread leg collar, allows attachment of peripheral equipment including camera, tablet, mobile phone etc via magic arm or ballheads.
Comes in 4 sizes according to the top section of tripod top section leg diameter, TDC-28/32/36/40
CF-9 allows attaching of 3/8" ballheads.
Do note the size of the tripod diameter has to be the same as the labeling.
Picture with sizes is provided.