The overall measurement of the hand shaft (A) is important when you are using a glass front on your clock. You must allow sufficient clearance in order for the hands to operate properly. The overall length is measured from the tip of the hand shaft to the case of the movement (A). Allow an additional 1/8" for cap nut or sweep second hand. The threaded portion of the hand shaft (B) is the part of the shaft which will secure your movement to the dial plate or wood. Measure the thickness of the material which the shaft must go through. Allow an additional 1/8" for mounting hardware.