A multi-layer puzzle having a base with a perimeter portion and a cavity that depicts a theme. The footwear has two opposite sides and lace-receivers disposed thereon. The scan signal generation module is utilized for generating a first scan signal and a second scan signal according to a first clock and a second clock having a phase opposite to the first clock. The tension-adjusting mechanism portion defines a plurality of interchangeable point of contacts with the resilient blades, which contact points having different positions relative to the neckpiece. The simplicity of generating the low swing, achieved by the feedback which may be implemented by only two transistors, is in contrast with the complexity introduced by some methods used by other logic styles for achieving low swing. The number of levels of hierarchy can be fixed in advanced or it can be determined from the content encoded.