the best-quality grease Shimano uses. Anything branded Dura-Ace that has ball bearings is packed in this exact grease
Shimano is very, very careful with the Dura-Ace brand. Nothing is called Dura-Ace unless Shimano fervently believes in its excellence. It might just be grease here, but the fact Shimano chooses to call it Dura-Ace is an indisputable testament to its quality.