This is an old stitch, known from the Danish Faeroe Islands and the Swedish city Halmstad. The real Snöstorps-knitting is knitted a little different from this, that is why I call this a variant. (The different is just a matter of lifting a stitch as if knitted or purled, due to a misunderstanding of the original pattern.)

The result is double knitted, thick and stretchy. Be sure to use a thicker needle than usually.