Double torsion springs are special springs with two torsion coil sections that function by receiving a twisting moment from both ends or one end. Their characteristics lie in their stable torque transmission capability and their ability to accommodate complex operating mechanisms that are difficult to achieve with a single torsion spring. For manufacturing, spring steel wire is precisely formed using multi-axis coiling machines or CNC-controlled spring forming machines, and heat treatment or surface treatment is applied as needed. Their applications are diverse, and they are widely adopted in places where reliable torque transmission is required in a compact space, such as hinges and locking mechanisms in automotive parts, door opening/closing sections in home appliances, office automation equipment, and precision instruments.