The successful development of the automatic four-corner edge carton sealer (GPA-50E + GPG-755E), an H-shaped carton sealer, has filled the gap in carton sealers for corner-edge sealing required by specific industries—especially the electronics industry and industries involving sea shipping. It is equipped with a 90° corner transfer machine and an air cylinder for automatic carton pushing; it can automatically seal the four upper and lower corners of cartons simultaneously, and can be combined with GPA/GPB/GPC models to form a complete H-shaped carton sealing system. This carton sealer is widely used in industries such as food, daily chemicals, and electronics.