The red band tells you the 3M Peltor H540P3 has two shells. Double shell (or twin cup) technology is an entirely new form of hearing protection - perfect for chainsaw use or operating a chipper or stump grinder. The double-shell minimizes resonance and provides maximum high-frequency attenuation. In addition, the acoustically connected inner and inner-shell give the highest possible low-frequency attenuation - loosely translated, they cut out chainsaw noise. However, you can still hear people speak (more-or-less)! The 3M Peltor H540 is slightly bulky (70 mm width), but they are the best earmuffs you can buy! Meets EN 352-3 standards. Hygiene kit available - sold separately.