I have used these flush cutters and they work as advertised.
However, they are more than a bit tedious since you have to insert
the wire in the correct hole each time you cut. If you are using the
gauge to cut repeated lengths, you have to remove the cut wire from
the hole out of the front of the tool - the gauge keeps the cut wire
between the back part of the cutter from coming out of the back.
If you need repeated exact lengths, you need it. If not there are
other cutters that do a reasonable job and are far easier to use.