In fishing operations, hydraulic jars are used to deliver an impact force to free the fish. Jars designed specifically for coiled tubing are generally flow-through and torque-transmitting. They are available in single-direction and bidirectional versions. The most commonly used jars are the hydraulic, time-delayed type. This jar does not rely on stored energy within the tool itself to regulate the force of impact. Instead, the hydraulic jar uses a fluid-metering system to regulate fluid transfer between the cavities of the tool when tension is applied by the coiled tubing.