EVANS HD (Heavy Duty) Dry drumheads offer an ideal balance between durability and sound response, with advanced attenuation of unwanted harmonics thanks to precisely drilled decompression vents. The HD Dry heads are made with a 5-mil outer frosted film thickness, a 7.5-mil inner film thickness, as well as a 2-mil dampening ring on the underside, and decompression vents around the entire perimeter to eliminate unwanted harmonics. The HD Dry heads feature a semi-defined attack, with a short sustain and slightly less bright tones than standard HD heads. These frosted heads also incorporate Level 360 technology.