Nice device, with one minor flaw.
Review by: steple, 2008-07-14
It's a nice device, except the minor flaw of the false sense of security (like others said before). The "I can't do anything wrong" thinking that it can cause might lead to the mistake of feeding in the rope in the wrong direction, causing the device to fail. If you do that with most tubers, it will either work equally well (if it is symmetric) or just provide less but still enough friction.
Don't buy this hoping to get rid of work and responsibility.