Billie Jean is the latest collaboration of In-Ear-Monitors (IEMs) between Astell&Kern and Jerry Harvey Audio which feature a new Dual Balanced Armature (BA) driver system. It is another winning product created by combining the experience and know-how of Jerry Harvey's IEM design and the quality production of Astell&Kern.Billie Jean brings to life a real audio experience that will take your music to the next level.Utilizing our experience of producing the award-winning SIREN Series IEMs, which is loved by music enthusiasts around the world, we were able to achieve a new level of accomplishment for those who enjoy a genuine music experience.Billie Jean features the patented freqphase technology from Jerry Harvey Audio with a new internal sound bore design to bring clear and impeccably balanced sound from sub-bass to brilliance range. The new IEM shell has been optimized to fit nicely in the ear, utilizes a 2-way 2-BA design, Silver Tinsel cable and L-type plug in a small, compact package. The result is a brilliant pair of IEMs designed and built by Jerry Harvey, the inventor of custom-IEMs, and Astell&Kern, the global leader in Hi-Fi audio.