After 440 kg load-bearing test and 25,000 cycles of push and pull test, the single door size can reach 3.5mx.2m, the frame and door fan are 2.2mm wall thickness, giving you a sense of security as stable as Mount Tai. Strengthen the hook narrow to 28mm, the visibility rate up to 98%, bring unlimited vision. The upper and lower rails are double pulley design, built-in double elastic auxiliary parts, and super size can also be easily operated, smooth push and pull. The lower rail is formed in one piece, and the heat insulation groove effectively improves the heat insulation performance. Embedded frame + four seals, bring a quiet life as low as 40 db.