I have not personally used these, but my guys in the field love them compared to the new DBI X2 and X3. We are currently working on changing out all of the safety climbs in the entire company to these. Will be purchasing more of these in the future.
Don't climb without these. Once they are attached to your harness, you don't even know they are there, but if you were hanging in your harness, you will be glad they are. Suspension Trauma can happen almost immediately to some. Don't take the chance.