1, the structure is different: the first-stage hydraulic hinge adopts single-sided torsion spring, and the second-stage hydraulic hinge adopts double-sided torsion spring and patented double bearing structure.
2. Different durability: the first-class hinge will have the problem of prying back and forth, and the wooden screw will slip when opened and closed many times. The secondary hinge will not have the problem of prying back and forth, and it is durable and has low noise.