Part of the D'Addario family, the global leader in musical instrument accessories, the Evans brand is synonymous with quality and consistency. Decades ago, Evans was the pioneer of drumhead manufacturing and design, and today they are the innovators. Designed, engineered and manufactured in the USA, Hydraulic Blue two-ply bass heads feature a thin film of oil between the plies that suppresses unwanted overtones, resulting in a classic sound, short in sustain, reminiscent of early 70's rock and roll. Hydraulics are famously easy to tune, making them perfect for troublesome drums or players with limited tuning experience. Tension it tight for a real thump or loose for a more slappy sound.