Patent ID: 8648677
Filing Date: 2014-02-11
Classification: H01H

Abstract:
1. A key comprising: a base defining a through hole, an inner surface of the base defining a helix slot; a convex lens received in the through hole, at least two protrusions protruding from an outer sidewall of the convex lens, the at least two protrusions rotatably engaging the helix slot to secure the convex lens to the base; and a plate securely received in the through hole and arranged below the convex lens, a label being sealed on a top of the plate; wherein when the convex lens is rotated by an external force to move along an axis of the through hole through the engagement of the at least two protrusions and the helix slot, the distance between the convex lens and the plate changes, and the size of the image of the label thus changes when viewing through the convex lens.