Simple metal poster clamp connector for joining multiple poster clamps together - for example, join 2 x 1500mm clamps for a single 3m long hanger. Just remove the plastic caps from the end of each clamp, slot the connector into each, push firmly together and tighten for a secure connection.
DON'T FORGET, you will need two for each pair of clamps - one for the top bar, one for the base bar.