Evans EQ4 series features a single ply of 10mil film. A fixed internal overtone control ring focuses the tonal response of the drum. The frosted surface provides a warmer tone. Evans EQ4 series features a special single ply of 10mil film that provides durability and a woody attack that speaks live and in the studio.. The fixed internal ring is proportional to the head size optimizing control from 18 to 26 . 26 drum head with fixed internal overtone control ring proportional to the size of the head An internal overtone control ring and a removable muffle ring coupled with dry-vents work extremely well with and without a microphone Single ply of 10mil film offers full wide-open tone Also available in a clear version All Evans drum heads are designed engineered and manufactured in the USA