It attaches to the other side of the shoulder (gallows).
It is designed for the cross arm in case you want to pull it to a greater height and/or load it with more weight. In that case, you must use this counterweight to balance the structure by attaching it to the other side of the arm (gallows).
You can combine several of them together to get the weight you need.
Reference: 51423185
Brand: B.I.G.
Reference: drr01483
Brand: Dörr
Reference: 575122
Brand: Hama
Reference: 51428260
Brand: B.I.G.
Reference: 5157037
Brand: Helios
Reference: big00481
Brand: Neurčená