These are a great idea, but a bit pricey. When you consider the cost of 15 feet of 5/8" Amsteel or Endura-12 (and how easy this stuff is to splice) a do-it-yourself version is an easy/smart thing to add to mooring pennants, IMHO.

I thought about Maine Sail's excellent post about mooring abrasion. BTW I don't have any affiliation with the companies.