The Rename button will change the suffixes (Ankle, Hip, Leg etc) of all the layers in the selected limb. To do this, it uses the names from the currently selected preset in the dropdown. So in our example, we could select the Right-Ankle layer, and with the Arm preset selected, click Rename. Limber then renames the layers to Right-Wrist, Right-Shoulder and Right-Arm. This is really handy if you duplicate a leg, intending to make it into an arm, for example.