I replaced the chain on my Eddy Merckx 3XM with the Campy ultra narrow and realized I should have done this a long time ago. Although my old chain was only at 50% of its life, this new chain is so much smoother. Well worth the upgrade.
This is the upgraded, slightly narrower version of the 10-speed Campagnolo Record chain that was introduced not too long before Campy changed their top groups to 11-speed. If you are still using 10-Speed Campy drivetrain, you can't go wrong with this chain. The previous Record chain, which was about 0.2mm wider, didn't last nearly as long. I average 100 miles per week, and I used to go through a couple of the older Record 10-speed chains in a year. This chain still checks good on a Park chain-wear gauge after more than three and a half years of use. I bought a spare from this web site but haven't had to use it. It's expensive for a chain, but I still give it four stars for value based on its longevity.
It's getting harder to locate, but Campagnolo chain is worth the added effort to find because it is a superior product. I've tried all the other 10 spd. chains on my Campy drivetrain, and none do the job as well as the Campy chain.