Yes, there is a special tool for crimping the connector onto the wire plastic insulation. This is an example of one. If so, technically, they are illegal for competition usage. Personally, I don't give a rat's ass about this. As long as there is decent conductivity, I'm fine with using it. Remember, you should solder the wire directly to alligator clip. However, you need to make sure the alligator clip surface is clean, use the proper type of flux, a high power soldering iron, rosin core solder, and plenty of patience. Oh yes, proper soldering is done by heating up the two parts hot enough to melt the solder. You may get a cold solder joint otherwise. Always use rosin core flux. Acid core flux (the flux the plumbers use to solder copper tubing) will eventually corrode the copper wire and give you problems later on. Don't ask why I know this. Last piece of advice, I remember once watching someone trying to solder a wire to an alligator clip. The only problem was that he had the alligator clip clamp between the jaws of a cast iron bench vise. The bench vise was acting as a heat sink and was absorbing most of the heat energy from the soldering iron. I corrected him by making a quick set of cheap man's vise jaws out of a piece of cardboard (business card). Afterwards, it didn't take him very long to heat up the alligator clip surface hot enough to melt the solder.