Like time itself, the design of the Dusk Wall Clock is ever-changing. Made from two disks of polarized acrylic that slowly turn with the clock’s movement, it adjusts its color and transparency as the day goes by. In the morning, it’s a light, transparent gray which gradually darkens to opaque black by nightfall. Easy to install (with included hardware) and calibrate to any time zone, the 12" diameter Dusk Wall Clock will quietly complement any decor. Requires one AA battery (included).