Does anyone know where I can purchase these?

thans,

Robertson Stykbow sells them through their online store.

http://www.tradout.com/categories/Archery-and-Bowhunting/Bow-Accessories/Limb-Bolts-and-Connexion-Hinge/

It works great on my bow, but looks challenging to install.

Thanks for the info...

If they are out of stock.... does anyone else carry them?

A friend got one from Stykbow a couple of months ago.   I googled and did not find another dealer, though Mohawk Bows is shown as offering them on their bows.

The installation is not that difficult, certainly not as difficult as metal sleeves or internal screws.   There is a detailed "hinge-along" on my site:   www.dickwightman.com    Covers both original installation and conversion