Ashtanga yoga practice makes you sweat! So normal yoga mats often get really slippery during practice. To accommodate, people often buy yoga towels to lay over the mat to prevent slipping and to soak up the sweat.
Yoga Design Lab's yoga mats are designed so that when you are sweating during practice you can still grip. However, you need to spray with water if you are not sweating a lot.
Its basically a towel and yoga mat combined.
You can even wash it in the washing machine if you want. I spray mine with organic cleaner in between use and wash every couple weeks in a bath of water with anti bacterial soap.
Image Source: Yoga Design Lab Facebook