Evans EMA13SD. 13 inch Marching Staccato Disk. The Marching Staccato Disk is a flat circle of Retro Screen mesh designed to suppress unwanted overtones. Particularly well-suited to indoor marching venues where maximum note definition is required. The Evans X-Treme Patch for marching is the ticket to drawing several sounds - what we call zones of expression - out of a single drum head.