175 grams of Courtelle or 200 grams of pure wool are called for.

The fabric is looped on the right side. Every other stitch on the right side is looped, thus:
Make loop by inserting needle into next stitch and winding yarn three times over point of needle and first finger of left hand, then over needle again. Draw loops through stitch but leave stitch on needle. Place loops back on left-hand needle and knot loops and stitch together through back of loops.

Wrong side rows are purled.