NUKOTOOLS is a maker of unique, innovative, and reasonably priced impact tools. The tools are designed to be discreet, last-ditch defensive tools. Each one is hand made from G-10 which is a non-metallic material that fits the discreet mission of the tool.
The Punch Ring (shown in the image above) is the most compact of the three tools that NUKOTOOLS makes. It can be easily carried on a key ring so that you always have it with you. It is extremely easy to use but, as with any defensive technique or device, it is more effective with training. The user places their middle finger through the hole in the center and then makes a fist. The chiseled edge protrudes forward of the fist and serves to concentrate the force of the punch. The broad base presses against the palm to reinforce the fist. Stay tuned for a full review of the Punch Ring.
You can view the full line of NUKOTOOLS on their website.
You should research the legality of these tools before carrying them.