Septum polarizers have been used in waveguide systems for over 50 years and are very popular in communication satellites operating in circular polarization. With the progress of computational electromagnetics and computer hardware. combined with advances in manufacturing techniques. there has been a growing interest in septum polarizers with smooth profiles. https://www.roneverhart.com/Toshiba-AL13SX-AL13SXB30EN-300GB-15K-RPM-SAS-12Gb-s-512n-128MB-2-5-Hard-Drive/