The key ring works very well using a mechanism that is hard to detect. They are in very good condition and look great. At this price point, we believe this is a good value for a used product.
We do not know the manufacturer. Obviously, they are not made from gold or are gold plated. Instructions are not included with this estate item — but we are confident you can figure out how to lock/unlock the rings and handle them properly. There are many routines in print using similar type of rings.