Noise Protection System For Microphones. SPK is a set of tools consisting of: ST2: Universal double support with 5/8" thread. SSM-1: Mechanical noise suppressor support. SPF: Pop filter for hard phonetic impact sounds. Independently of the above units having their individual functions, their joining into a kit transforms them into a powerful tool in studios, as well as on stage. The mounting options are endless, depending only on your imagination and creativity.