It's a Chinese cable you can get on Aliexpress cheaper. You can also choose different lenghts.
https://www.aliexpress.com/item/Cable-for-Sennheiser-Headphone-HD525-HD545-HD565-HD650-HD600-HD580-Headphones-Replacement-Audio-Cable-Cords-3/32813538340.html?spm=2114.search0104.3.43.3427dbe35CmkTQ&ws_ab_test=searchweb0_0,searchweb201602_5_10065_10068_10843_10059_10884_10887_312_10696_100031_10084_10083_10103_10618_10304_10307_10820_10301_10821_528...