Soles are covered with natural latex which makes them not slippery.
Now slippers available with rubber soles. Follow here if you are interested https://www.etsy.com/listing/100254500/rubber-soles-for-felted-slippers
Felt is a perfect material for footwear. It is especially wear proof and warm. When you put your slippers on, you won't want to take them off. They'll become as a part of your home outfit, as a part of your Home.
Try JurgaZa slippers! And you love them!
If this size doesn't fit you, I can make these in any size you need. If you prefer to have mule style slippers, let me know, when ordering, please.
Usually it takes 5-7 workdays to make a new pair and 1-3 weeks to ship.