Abstract: An adjustable shoestring includes an elastic shoestring body and a fastener coupled to the body. The body includes an elastic rope ribbon, a buckle hole, and engaging balls spaced equidistantly configured on the right side of the rope ribbon. The fastener includes a through hole allowing the right end of the body to be passed through, a buckle stub buckled with buckle hole and a slot engaged securely with the ball on the right of the ribbon; the through hole allows the balls on the ribbon to be passed through. Engaging balls may be configured on the left side of the rope ribbon optionally. The adjustable shoestring device can be properly adjusted depending on the size of a foot. The present invention has multiple safety designs, and the end portion of a longer shoestring may be cut off. The shoestring will not be treaded and a person wearing a shoe with the shoestring will not fall down.

Abstract: A workpiece has a glossy coating layer disposed thereon. A barrel plating device is electrified with an alternating current, which has a voltage between 1V and 100V, a current density between 0.02 A/dm2 and 50 A/dm2, and a frequency between 1 Hz to 60 KHz. The alternating current is rectified by a low ripple DC rectifier into a direct current whose ripple coefficient is between 0.3% and 26%. Thereby, a surface of the workpiece is electroplated with the glossy coating layer, which contributes to a glossy and even effect on the surface of the workpiece.