So far, the design and functionality are amazing. As a veteran, the necklace has helped me exponentially. I quit smoking because of it. I can immediately fall into a state of meditation when I breathe into it. I don't just blow into it. I use it to have resistance to my breath, forcing me to focus even more on the present moment. Also creating a form of resistance training for breathing. You guys came up with a stellar product. This product is for sure underestimated in its value and application. I appreciate the cheap price for the quality of the material too.