Here is the place for HT
shackles. The only problem is that they have only two sizes ˝ and 3/8. But I believe that 3/8 will do it for 5/16 chain.
http://store.hamiltonmarine.com/browse.cfm/2,565.html
Those titanium
shackles look very interesting. Thanks for the link, GordMay.
Max.