It is an original ear pad from Audio-Technica for ATH-M50X and that probably says everything. It is designed for these headphones and sound-wise it is probably the best.
However, I am disappointed in thomann. At first I thought it's my fault and I'm the only one who expected it to be a pair. But after reading the reviews I understood there were countless buyers like me. Why e.g., B&H Foto could come up with visually clear image that it is only ONE ear pad, not two like usual? – thomman, even after dozens of users mistakenly have bought only one ear pad did nothing as of yet.
All in all, it's a great product, but if I could rate thomman's description separately, I'd probably give it only ONE (1/5) star. While thomann's customer service probably deserves 5 stars for offering a free shipping for additional item.