The previously-reviewed Cable Slitter reminded me of this little thngamawhoogy. My father, who made his living as an electrician, always had one on him for stripping cable. You slip it over the wire however far you want to cut it. The electrical cable passes through a hole in the wide end of the CR-100 (note: the holes running along the side are only for checking the gauge of the wire). Then, gripping the tool firmly, you just slide it toward the end of the wire, pulling the wire through and causing the cutting blade on the open end to slit the length of the sheathing, without damaging the wires inside. You can then pull the inner wires out and cut off the sheathing with a knife. Or in my father’s case, the cutters on his pliers. This Cable Ripper and a pair of pliers was all he ever used (he could also strip wires with pliers, but that’s really an acquired skill).
It’s virtually impossible to accidentally cut yourself with this tool, which makes it safer than trying to slit a cable with only a utility knife. I also find it’s better than the strippers on a set of pliers, because it’s specifically made to slit romex (NM or non-metallic) cable, not strip insulation off the wires themselves. Two drawbacks: it’s intended for romex cable and really isn’t too useful for anything else. Two, you need another tool to cut the sheathing off. Still, it’s inexpensive, works great and you can get them at Lowe’s, Home Depot or any electrical supply place and probably your local hardware store.