The cover for my Kindle 4 is a lighted cover from geckocovers.com from the Netherlands. The light was flickery on it, so I asked customer service what to do about it, and they sent me a replacement light to install. After I put it in, worked like a charm. It is the best light I have ever seen on an e-reader. I use it at night or in places with dim lighting.
It has no clasp, but magnetically stays shut.