Specifications: 1) Vertical steel keel: A) QC75 x 40 x 0. 4, 0. 5, 0. 6mm B) QC100 x 50 x 0. 5, 0. 55, 0. 6mm 2) Transverse steel keel: QU75 x 40 x 0. 6, 0. 7, 0. 8mm