The double-needle roller sewing machine (main models 9920/692) is a column roller-type double-needle lockstitch machine, specially designed for sewing thick curved materials like leather, shoe materials, and bags. Its core uses a synchronized feeding system with upper roller, lower roller, and needle, allowing the two needles to form two parallel stitches at once. Traditional flat sewing machines can easily cause material slipping, skipped stitches, or difficulties sewing curves in leather. Ordi