The Benro BL75S is a 75mm Half Ball Adapter with Short Tie Down Handle.
This will fit the HH75AV 75mm video hi-hat as well as any standard 75mm video tripod bowl.

The Benro BL75S 75mm Half Ball Adapter features:

– Compatible with 100mm video heads with 3/8″-16 tie down stud
– Short tie down handle for low to the ground tripod setup
– Aluminium construction