Tried almost all of them (seriously I have) and these are hands down the BEST for the 10/2 to 18/2 stranded wire that we use so much of in our industry.
Why are they the best? Well they will never cut a strand! Even if you try to make them cut a strand they will not. Totally automatic you don't have to fit the wire into specific size cutter. Never a cut strand again.
To those who have tried them and don't like them... well I once watched an electrician try mine out. He put both conductors in the tool and tried to strip them both at the same time. It didnt work too well. He "humph'd" and asked what the big deal was. I then showed him with just one conductor at a time in the strippers.... a perfect job with very little effort. 'Ahhh' He said.
If you can find identical, generic ones buy them and save some $. I get a generic type at a local hardware store. Each of my guys gets a new one each year and they tend to last about that long.