The purposes of jaw type spiders include joining hubs, absorbing vibration and accommodating slight degrees of misalignment as power is transmitted in manufacturing and industrial processes. Composed of flexible rubber polymer (primarily Buna N, or Urethane) a flexible spider insert joins the hubs of jaw type couplings and acts as a cushion between them, thereby reducing the force of impact loads. Items vary by dimension, maximum torque, maximum RPM, coupling size and other considerations.