Double-sided tape 4 mm wide, 50 m.
This tape is intended to adhere different layers together within the seam allowance so that they can no longer slide during sewing. Super handy for sewing zippers!
Attention, do not sew over the tape, this to avoid sticking your needle!
Since you usually sew with a seam allowance of 1 cm, this tape can be perfectly adhered within the seam allowance without being sewn over it.