The difference is (not quite) clear. An instant classic combining two 7.5-mil specially-treated, semi-opaqueplys, in REMO's patented Crimplock high-tension collar. Created especially for a distinctly warm, dry sound. Popular among many drum corps, marching bands and indoor marching ensembles.Remo Suede Emperor BE-0808-MP 8 Inch Marching Tenor Head, CrimplockTwo 7.5 mil plysAvailable in sizes from 6-14 inchesWarm, Dry SoundHigh Tension Crimplock Collar