Hi Shayne, The Freino carabiner will help to increase the friction through the belay device, but it is no substitute for a prusik. It is possible to rappel without using a prusik, however, it is much, much safer to use one. There are also many situations where you may need a spare hand while abseiling, like stripping quickdraws from a sport route or building the next rappel anchor on a multi-pitch decent. In these cases especially, it is highly recommended that you use a prusik. Hope that helps, Dave