It's a $5 roll-on liquid which dehydrates the skin, and one of the best anti-perspirants that I've used. One usage will keep your skin dry for several days. You can get it on Amazon.com, and by the way, I'm not affiliated by either company.
It doesn't just worn on the underarms. I've tried it under my chest during a hot summer day, and I did not sweat at that area once.
One thing, though, it is unscented. What I recommend though, is that you spray your favorite fragrance onto the roll-on (about 8 to 10 times), roll it and then shake it. I sprayed Fahrenheit into it. 6 months later, it still smells like Fahrenheit (rather than body odor).
So definitely check it out. Easily the best anti-perspirant that I've used. It's much more professional to go to work on a hot summer day without sweating into your dress shirt.
It's the only thing that truly works for me. I can't use it too much as it starts to make my armpits burn, but I'll use it about once a week, and normal deodorant the rest of the days to help the pits not smell.