When discussing shears with stylists and barbers, the first question, which comes up, is usually how long the shear is. So how do you measure a pair of shears?
In the most simple terms, when salespeople talk about shear length, they are (or they should be) talking about the overall length of the shear. This is the length of the shear from the tips, to the furthest point on the finger ring, but not including the finger rest. [We don't include the length of the rest in the measurement, because in many cases it is removeable, and the overall length of the shear shouldn't depend on whether the stylist or barber has removed the rest or not.]
Also important in the shear's measurement, is the length of the blade. The blade length is the length of the shear from the tips of the shears, to the center of the pivot. Many crane-handle shears (like on the Hikari #B2 shown in the picture you saw when you clicked into this post, or on the Mizutani Acro-K shown at the bottom of the page) have a pivot, which is located closer to the tips than a semi-crane (shown in the picture of the Hikari E-Series shear, directly below), or a levelset shear, and so will have a shorter blade length. The length of the blade will affect both the cut and feel of the shears. When trying out a new shear compare the two to see which one feels more comfortable to you.