From the Glerups website: 

Glerups slippers are made of 100% pure, natural wool in the classic colour denim with a sole of soft and chrome-free calfskin. We started making slippers over 30 years ago - in fact, our founder Nanny Glerup made the first pair of slippers as a declaration of love to her husband Ove.

All slippers are produced in our own factory and in our special glerups wool mix, which makes the slippers itch-free and durable. All slippers are designed and produced with respect for animal, people and nature.

Choose the shoe model if you want the "shoe feeling" when wearing slippers and want to give you and your feet a little extra comfort.