Brave citizens of the tumblr: Do not be fooled by term needless injection or the excitement your doctor may exhibit upon the mention of such a system. Instead of thinking "oh boy, no needle" you should be thinking "how the fuck do they plan to get that into my body". And when they tell you with great enthusiasm that it's air pressure, this is what you need to think about: Getting hit at point blank range (less than inch) with a shot from a high fps airsoft gun. The air pressure has to break your skin, okay. That means a much bigger whole than a needle, and a lot more residual pain. The aftermath looks like you pissed off the mosquito from hell.