These are the Gamemaster's Slippers. They can not be dropped by any mob. Typically, only Gamemasters have this equipped, proving they are indeed a Gamemaster. If you see a normal player wearing these and they do not have anything indicating that they are a Gamemaster, they obtained them through some sort of exploitation method.
You can see some in game screenshots of GM wearing this as well Robe and Hood in one of the comments for Martin Thunder (http://classicdb.ch/?item=192).
It took me some time to actually get a GM to make himself visible to me to actually get you guys a proper view of it from an actual Official GM. But here they are. This cost me a Permanent ban. And a possible IP ban. So I hope you guys appreciate it.