Jaw couplings are composed of three parts: two metallic hubs and an elastomer insert called an element, but commonly referred to as a "spider". The three parts press fit together with a jaw from each hub fitted alternately with the lobes of the spider. Jaw coupling torque is transmitted through the elastomer lobes in compression.The elastomer of the spider can be made in different materials and hardness, which allows the user to customize the coupling to best serve their application. Considerations for elastomer selection include ability to dampen vibration, ability to handle misalignment, operational temperature range, speed of equipment, and chemical conditions.