I have one of the Specialized tools like this one and the chain would never sit straight in the breaker. Also, you can't see it in the photo, but the breaker has a hole on the other side for a wrench or screwdriver so you can put torque on it... so you have to carry another tool to use it. Eventually the pin in the breaker folded over and that's when I benched it.

I have another tool that comes apart into three different wrenches with multiple ends, rather than folding out like a jackknife. It works well, but it seems like one of the three pieces is always lost. I couldn't tell you the brand, offhand.