These compact single AA battery-operated quartz movements are available in a choice of three shaft lengths — 1/8", 1/4" or 3/8". The shaft length is the threaded portion that will fix onto the dial plate or piece of wood. Choose the shaft length based on the thickness of material to be used. All shaft diameters are 5/16". The dimensions are 2-7/32"×2-7/32"×5/8". Batteries not included.