It basically is a c-clamp, but it has a pin that mushrooms the pins on the chain. If you do not have the tool but have the correct number of links you can just use a clip link instead. It's not supposed to be as strong as the rivet link but I have used tons of them and had no problems. For extra security you could allways wrap and twist a piece of stainless safety wire around the clip part of the link... That's what I do anyway. You could get away with not buying the tool if you are going to use the clip link. Technically you are still supposed to use the tool to press the link together before you clip it, but you could get away with a clamp if you just need to do that.