Abstract: In a preferred embodiment, an elongated material has slits extending from a central portion in parallel arrangement along the elongated direction and an upper material is stitched to a lower material through the elongated material for a greater part of the common widths of the elongated material and the upper and lower materials, but also stitched between the upper and lower materials for the remainder of the common widths but only through the slits for thereby making possible withdrawal of material only adjacent and between stitches of the remainder of the common widths such that a closed compartment space formed between the intermediate elongated material and the third or lower material is accessible through slots of the slits where material has been withdrawn only in an area of the remainder of the common width where the stitches do not engage the elongated material.