Highlights. Average loss of accuracy less than 1 second/day. Technical Specifications: Average deviation: Loss of accuracy less than 1 second/day at 21 degrees C. Clock hand length: 21 mm. Dimensions: (W x H x D) 56 x 57 x 16 mm. Model (clocks): Quartz. Power supply: AA battery (1x), please order separately. Description: Needle shaft length 21 mm for stronger dials, (e. g. wood, stone, marble, etc.).