This is a replacement black /Manfrotto Expan Drive Metal Chain. Metal beats plastic for strength and longevity, as far as Expan Drive chains go. It is 11.5' (3.5 m) long.
This item replaces old catalog #2924.
replaced the breaking plastic chain with this one and all was good.
I had to switch from the plastic ones, which were just not working and snapping off all the time. This ones geet the job done, but the weight used for the plastic chain doesn't fit the metal one. They also twist and get tangled in little 'knots' often. I'll live with them as the are much better than the plastic, but I think the design needs some work, to avoid the twisting.