This stitch looks best when contrasting colours are used.
Multiple of 2.
Abbreviations: C: colour; sl 1: slip 1; k: knit; rep: repeat; p: purl
Row 1: C1: *sl 1 purlwise, k1*, rep from * to * until end
Row 2: C1: p
Row 3: C2: *k1, sl 1 purlwise*, rep from * to * until end
Row 4: C2: p