Manfrotto 

Boom Pivot Clamp 

Heavy Duty Model

35mm Diameter Fitting for Boom Poles

Please note: 

This is the Heavy Duty Pivot It will not fit a regular manfrotto light stand without 

purchasing an extra fastening screw for the hole on the side,

by default it fits the heavy duty ones only, 

it slots into the larger fitting 35mm hole on the heavy duty stands.