For years, I'd tried every tool I had to stop the chainring nuts from slipping when tightening, but nothing worked. This tool does the job and is cheap. If you don't have one, pick one up before you need it.
This is a solid tool with most everything needed. Manufacturer says the tool weighs 136 gram (this site says .3lb which is the same). Actual tool weighs 179 grams which is a big miss on published weight. Big deal? Maybe not, but I bought this for bikepacking racing where little stuff like this adds up. A little disappointed in the misleading specs.
I spray this on my chain with a rag behind it and gunk flies off onto the rag. Then a wipe down of the chain, and it is ready to be re-lubed. I have read reviews of people spraying this on their cassette. I don't recommend that as it can get inside. I spray it on chain floss (or a thin piece of cloth) and clean between each gear with the rear wheel off. I have had mechanics tell me my bike is cleaner than they will get it.