I mentioned the swivel earlier and here it is. A swivel is a critical part of any permanent mooring system. In Falmouth, Maine it is an enforced ordinance that you use a swivel.. They are also one of the biggest weak links in any mooring system.
Because I know swivels are weak links, & wear items, I purposely use over sized eye to eye swivels. This one is made by Campbell and was purchased through Hamilton Marine (#106233). These are not the cheap Chinese imposter products that have flooded the US market, they are high quality load rated swivels made right here in the USA. If I recall this is a 1" swivel and it still gets replaced every 2 to 3 years.