Whether your hobby is Radio Controlled Aircraft, Cars or Boats,  you will need linkages to operate the moving parts between the Servos, and the control surfaces. Control linkages consist of levers, joints and other moving parts that allow a servo to move a control surface. There are many available options ranging from various materials, to different sizes and weights, depending on what is needed for operation and specific model requirements. For a modeller building from scratch or from a kit, proper selection and assembly of these mechanical components can be critical.