I'm seeing a few different types of collars, from something called a Peanut No. 9 or something of the sort as well as Heartcore. From what I understand in reading the description, Heartcore collars are intended to be much more restrictive for the wearer, once an owner is assigned to it. And from what I've been told by another player, it's impossible or perhaps they just meant difficult for the wearer to remove anybody assigned to it as owners. Couldn't this be problematic if perhaps a submissive person found themselves an owner who suddenly stops signing in, for example? The idea sounds intere