I had been longing for sippers with a lining such as this for some time, just always bought inexpensive slippers for years.  This year I splurged and actually tried other brands, which I ended up returning.

These mold to your feet, don't slip, and are the most comfortable slipper I've ever worn.  I'd have expected my feet would overheat and moisture might be a problem.  Not so.

The sizing is right on; I wear a 1/2 size and bought the next size up (a size 9).