ATTACK DH20P Ported Bass Percussion Effect<div style="text-align: left;"><strong>[Product Information]</strong><ul><li><span class="a-list-item"> 1 ply front heads </span></li><li><span class="a-list-item"> 4" diameter port </span></li><li><span class="a-list-item"> Reinforced for added strength and durability </span></li></ul></div><img src="http://ecx.images-amazon.com/images/I/31Of7Mz9trL.jpg" noproxy>