I have some of this stuff:
http://www.selfdefenseproducts.com/pepper.htm
The wind as mentioned is a concern with this stuff though. Even though it does shoot about 10 feet it can blow back. On the day I tested it on a tree I got just a tiny bit of it back into my throat. Just an extremely small amount. It burned and choked me far more than any Mexican food I've ever eaten. I hate to think what it would do to the eyes, and I can't see anyone doing much after it hitting them, regardless of comments condemning pepper sprays.
The amount that blew back on me was just some drizzle and it really stung.