For most of us, earbuds--the tiny in-ear phones that come with most portable music players--are a less than exact science. They're usually loose, and when they are, you lose bass response and let in extraneous noise. Sonomax thinks it has an answer. The company uses a system that injects a moldable foam into your ears so that the fit is perfect. Normally, to get a custom fit would take the aid of a professional, but the use-once-and-toss silicone injector gets the job done in minutes.