The Revolver's pulley wheel reduces friction on ropes moving through the carabiner. Placed where the pitch changes direction, it reduces rope drag and makes upward movement easier.
The Revolver can be used in an improvised hauling system to help your second over a crux, haul kit bags, or rescue your partner from a crevasse. Where normal carabiners in these systems cause energy to be lost as friction, the Revolver's pulley wheel makes hauling easier by converting more of your energy into movement.
A Revolver on your rack lets you reduce rope drag and make efficient mechanical advantage systems without the need for additional devices.
An overview of the features and benefits of the Revolver carabiner.
I think the DMM Revolver is one of the more underrated climbing inventions of recent times. Though this specialty carabiner has been on the market for the last five or so years, it deserves another look for its multiple applications to a wide array of climbing situations.
Andrew Bisharat - eveningsends.com