All-in-One Boots Combining high heels with warp knit stay-ups, the thigh-high boots elegantly contour the legs. The boots feature front and back seams, with hotfix logos placed on the back. A hidden silicon strip around the upper edge ensures the perfect fit. Warp knit technology / Front and back seams / Invisible silicone stripe at the upper edge for perfect fit / Hotfix logos placed at back seam / 10cm heels main material 87% polyamide, 13% elastane S40 is slightly smaller than M40 in terms of tightness. However, the model wear both S40 and M40 and did not feel much difference in tightness and length. Both of them are comfortable and stretch well.