The grille of a speaker.
"I have been listening to the CD's you sent me. All the ones I've heard so far sound fantastic! They are clear and crisp. I can't detect any scratches or pops and the highs sound very clear too. I did not detect any reduction or muffling of the highs. I am very pleased and impressed. You did a great job! I will send my next order to you in a few ..."