This is a newly designed reinforced connecting pin for CN-7801 & CN-6600. It cannot be used with the older CN-7800 (Original Shimano 10 speed chain). It's easily identified from the older 10 speed joining pins as it's guide part is longer and comes with 3 grooves on it. Click here
for Shimano's Technical Service Instructions for chains (unless they've moved it!) Weight: 1g.