Manfrotto 036MR Stud Lighting Hexagon w hole for safty cable for lights also for joining 2 superclamps

The Avenger E300 5/8″ Stud with 1/4-20″ Female Thread screws to the top of a light stand, stud or accessory that ends in a male 1/4-20″ thread. It lengthens and strengthens an existing fixture mount.

16mm female adapter.

This double male adapter features 16mm (5/8”) pins on each side.