the equipment for transporting and using coiled tubing, including a reel for the coiled tubing, an injector head to push the tubing down the well, a wellhead blowout preventer stack, a power source (usually a diesel engine and hydraulic pumps), and a control console. A unique feature of the unit is that it allows continuous circulation while it is being lowered into the hole. A coiled tubing unit is usually mounted on a trailer or skid.