After Campagnolo spent huge resources in developing the much ballyhooed 11 speed group, they haven't sat on their laurels. They took a well engineered chain and made some nice improvements. The outer plates have been re-profiled for quicker shifting and better performance - they are quieter too. The links also received a Ni-PTFE coating which helps chain glide, reduces drag and adds life to the chain. Pins are hollow for weight reduction.
The 5.5mm width is designed to fit Campagnolo 11 speed drivetrains only.