Must have in your toolbox. I recommend buying a pair to use in opposition. Honestly, once you have a chain vise, you'll wonder how you ever managed without it. These are by far my favorite instruments. I've just bought a second pair because I packed them in a padded checkered case that was crushed on a trip to a distant international lab. The wrenches were bent beyond use and I was 10,000 miles from any hope of replacing them. I was seriously upset and had to settle for substandard arrangements for a few months. Now I have corrected the situation and also learned a good lesson that I should have foreseen. When you travel, pack them in a secure box that won't crush or consume your carry-on luggage.