Abstract: An orthodontic appliance for orthodontic treatment includes first and second eyelets connected to coil spring at each end of the coil spring, thereby forming a double eyelet and spring unit. In one embodiment, a connector for detachably attaching a spring to an orthodontic appliance includes a means for engaging an appliance. In one embodiment the connector is an eyelet having an aperture in its central region for allowing the spring to be detachably attached to the orthodontic appliance. The aperture may have a variety of shapes. Alternatively, the connector may comprise a hook or equivalent structure for facilitating the spring to be attached to the orthodontic appliance.