From website:

NL10 - FELTED (FULLED) SCUFF

This backless slipper is constructed same as the FELTED SLIPPER. Double pointed needles and bulky yarn make a thick and warm scuff. Add leather soles to the bottom to increase the life of the slipper. A washing machine makes the felting easy and fast.

SIZES: Shoe sizes for toddler 9-13, child 1-4 (women 6 -7 ½, women 8-9, men 10-11)

YARN: Bulky, 100-200 gms of 100% non-washable wool

NEEDLES: Double pointed #11

See also NL8 Felted (Fulled) Slippers