Pat, over here not many people have heard of the rack or genie, I've used the rack when working in Canada and didn't like it. The 'STOP' or 'ID' made by Petzl are the most common descenders over here as they are very user friendly and will stop or slow down the descent if the worker lets go of the rope completley, there is also a back up device, usually a shunt or a new one called the ASAP, all made by Petzl. Here is a pic of our set up, it's not very clear so I will try and find a better one after I've been for my christmas dinner